Final Exam

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What is a result of transposable elements?

The red color of some grapes is due to the action of a transposable element.

What might be the result if breakdown of the shugoshin protein were premature?

The separation of sister chromatids would occur prematurely.

List phenomena that can alter expected Mendelian phenotypic ratios in genetic crosses.

(1) Linkage (2) Epistasis (3) X-linked genes (4) Lethal recessive alleles (5) Environmental effects (6) Continuous traits (7) Variable expressivity (8) variable penetrance

List three observations consistent with the idea that cancer arises through an accumulation of mutations in several genes that promotes cellular proliferation in single cells.

(1) When single tumors are dissected and carefully analyzed, tumor cells typically contain anomalies in several different chromosomes. (2) Several different tumor-suppressor genes have been shown to encode enzymes necessary for DNA repair. (3) Early stages of colon cancer have a limited number of mutated tumor-suppressor genes and mutated oncogenes while later stages have several additional mutated genes.

The mosquito Aedes aegypti has a diploid number of 6 chromosomes. How many DNA molecules and Chromosomes are found per cell when this cell is progressing through the following stages: After Anaphase II of Meiosis the cell has ___ DNA molecules and ___ Chromosomes

12,6

If the recombination frequency between genes A and B is 15%, how many map units apart are they?

In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of the allele a is 0.1. What is the percentage of the population that is heterozygous for this allele?

If a prize can be found under only one of the three shells, and the possible prizes are a quarter (8%), a bottle cap (80%) and a hermit crab (12%), what are the chances of lifting a shell and finding the crab?

Which nucleotide is in the wobble position for a tRNA 5'AGC 3'?

How might gene duplication provide a mechanism for the addition of new genes with novel functions?

After a gene duplicates, there are two copies of the sequence, one of which is free to change and potentially take on a new function.

If a female Drosophila that is heterozygous for a recessive X-linked mutation is crossed to a wild-type male, what proportion of female progeny will have the mutant phenotype? A) 100% B) 0% C) 33% D) 25% E) 50%

Discuss unique two manners by which a child can end up with Down's Syndrome. (you must be very specific and explain what causes each manner for full credit/give specific names)

Cases of Nondisjunction Down's Syndrome occur as random events during gamete formation. Nondisjunction happens when either the egg or sperm ends up with three copies of chromosome 21. Mosaic Down's Syndrome occurs as a result of the mutation of chromosome 21 very early in fetal development. This means that some cells will have a normal pair of chromosome 21, and others will have three copies. Translocation Down's Syndrome results when a parent's chromosome 21 and another chromosome (either 14 or 15) translocate. The parent does not show signs of Down's Syndrome because they have no extra genetic material, just a mutated arrangement thereof.

What kind of test can determine whether genotypic frequencies match the Hardy-Weinberg model?

Chi-square with three rows (homozygous dominant, heterozygous, homozygous recessive)

Two gene loci, A and B, assort independently, and alleles A and B are dominant over alleles a and b. What is the probability of producing an offspring with the AB phenotype from a cross of AaBb ¥ AaBb? A) 1/4 B) 1/2 C) 1/16 D) 9/16 E) 1 (100%)

What is the flow of genetic information during gene expression?

DNA → RNA → protein

The genetic code can be described as:

Degenerate

Gel electrophoresis can be used to separate DNA on the basis of: A.size. B.electrical charge. C.nucleotide content. D.the probe used. E.both size and electrical charge.

E.both size and electrical charge.

Fragile X syndrome can strike at an earlier age and bring about a more rapid degeneration and death in successive generations within a family. This phenomenon can be explained by which mechanism?

Expansion of a trinucleotide repeat in the coding sequence of the gene

True of False: There are no transposable elements (also known as transposons or jumping genes) in the human genome

False

True or False: A chromosome with a centromere near the end is called telocentric

False

What is a dominant epistatic gene?

In dominant epistasis a dominant allele, if present, determines the phenotype of a given trait regardless of which alleles are present at the hypostatic locus.

Given the following chromosome : MNOPQSTU*V Which of the following is an example of a duplication of PQ and deletion of STU? ( * denotes the centromere)

MNOPQPQ*V

DNA contains a thymine dimer. What is the most probable DNA repair method that will be utilizes to fix this damage?

Photo reactivation repair

What sequence would not be found on a eukaryotic mRNA molecule?

Promoter sequence

Which of the following is not a similarity between DNA and RNA? a) Structure that includes pyrimidines and purines b) Remain in the nucleus at all times c) The capacity to store genetic information d) Phosphate backbone

Remain in the nucleus at all times

How are Hfr strains of bacteria different from F+ strains?

The F factor is integrated into the bacterial chromosome in an Hfr strain

What is a possible effect of mutations in genes that influence chromosome segregation during division?

This can lead to aneuploidies. Aneuploid cells likely contain losses of tumor-suppressor genes and gains of oncogenes, which would help promote cancer.

Thymine and guanine can pair through wobble between normal bases. (True or False)

True

What are the stop codons?

UAA, UAG, UGA

Which human genotype is associated with Turner syndrome?

Genes come in different versions called

alleles.

Reporter genes

can be inserted next to a "gene of interest" and expression of the "gene of interest can be followed throughout development

The Ras signal-transduction pathway

conducts signals from growth factors and hormones to the nucleus and stimulates the cell cycle

What type of synthesis occurs on the leading strand

continuous

Attenuation in the trp operon of E. coli is the result of

coupled transcription-translation

Heavy acetylation of histones is associated with

increased transcription rate

Which of the following types of DNA repair mechanisms does not repair pyrimidine dimers?

mismatch repair

A linear DNA fragment is cut with a restriction enzyme to yield two fragments. How many restriction sites are there for the enzyme in this fragment? A.one B.two C.three D.four E.It cannot be determined with this information.

A.one

Which of the following crosses would produce a 1:1 ratio of phenotypes in the next generation?

Aa x aa

What role do acetyltransferase play in the acetylation of histones?

Acetyltransferase are enzymes that add acetyl groups

Which of the following choices lists the CORRECT sequence of gene expression during Drosophila development? 1. Segmentation genes 2. Egg-polarity genes 3. Homeotic genes A) 1, 2, 3 B) 2, 3, 1 C) 2, 1, 3 D) 3, 2, 1 E) 3, 1, 2

Bacterial cells containing an F plasmid that has acquired bacterial chromosomal genes are called

The R locus determines flower color in a new plant species. Plants that are genotype RR have red flowers, and plants that are rr have white flowers. However, Rr plants have pink flowers. What type of inheritance does this demonstrate for flower color in these plants?

incomplete dominance

Alternate splicing

is seen in the insulin receptor mRNA

Suppose in flies, red eyes are dominant over brown eyes. If for this trait, a homozygous dominant fly is mated with a heterozygous fly, what is the probability that the fly will have brown eyes?

Give the RNA molecule sequence transcribed from the following DNA sequence from a eukaryotic gene and label the 5' and 3' ends. DNA: 5'-ATAGGGCATGT-3' 3'-TATCCCGTACA-5' <--- template strand

5'-AUAGGGCAUGU-3'

Which of the following order of gene groups is CORRECT for normal Drosophila development? 1. Gap genes 2. Homeotic genes 3. Pair-rule genes 4. Segment-polarity genes 5. Egg-polarity genes

5,1,3,4,2

In Mendel's peas, yellow seeds are dominant to green. A pure-breeding yellow plant is crossed with a pure-breeding green plant. All of the offspring are yellow. If one of these yellow offspring is crossed with a green plant, what will be the expected proportion of plants with green seeds in the next generation?

50%

Research on a population of mice has shown that there is forward mutation rate from black to spotted alleles of 10% and a backward mutation rate (from spotted to black) of 25%. In a population of 800 mice, with 60% of the alleles being black, how many black alleles would you expect to find in the next generation?

512

More research on hippogriffs has shown that there is also a backward mutation rate of 10% (i.e., from gray to black alleles) . Starting with a population of 600 black alleles and 400 gray alleles, with forward and backward mutation each 10%, how many black alleles would you expect in the next generation?

580

Hippogriffs can have black fur or gray fur. However, there is a high rate of mutation from black alleles into gray alleles. In a population of 1000 hippogriffs, if there are 800 alleles for black fur and the forward mutation rate (ie., from black to gray) is 10%, approximately how many black alleles should be expected in the next generation?

720

Out of 10 people (20 alleles), if there are 16 alleles for tongue curling (dominant over non-tongue curling), what is the minimum and maximum number of people who can exhibit the trait?

8, 10

How many different combinations of maternal and paternal chromosomes can be packaged into gametes by an organism with a diploid number of 2n = 46?

8,388,608 = 2^26

Two gene loci, A and B, assort independently, and alleles A and B are dominant over alleles a and b. What is the probability of producing an ABphenotype from a cross AaBb × AaBb?

9/16

If in humans, brown eyes are dominant over green eyes, and two heterozygous parents have three children, what is the probability that at least one of the kids will have brown eyes?

98.5%

Describe the pattern of a mitochondrially inherited trait you would expect to see on a pedigree

Affected mothers pass the trait to all of their children

Which of the following is NOT a common characteristic seen in pedigrees for an autosomal dominant trait?

Affected person can have an unaffected parent

What role might segmental duplication play in evolution?

After a segmental duplication arises, the original copy of the gene can continue its function while the new copy undergoes mutation. These changes may eventually lead to new function.

What common features of heredity suggest that all life on Earth evolved from a common ancestor?

Despite the remarkable diversity of life on Earth, all genomes are encoded in nucleic acids. With few exceptions, the genetic code is common to all forms of life. Finally, the process by which genetic information is copied and decoded is remarkably similar for all forms of life.

Briefly describe when and how Dolly the sheep was cloned.

Dolly the sheep was cloned in 1996 by researchers at the Roslin Institute of Scotland. Workers isolated the genetic material from a single differentiated udder cell of a 6-year-old adult, white-faced, Finn Dorset ewe, fused this genetic material with an enucleated egg cell, and stimulated the egg electrically to initiate development. After culturing the modified egg in the laboratory for a week, they implanted the embryo into a Scottish black-faced surrogate mother. Dolly, the first mammal cloned from a differentiated adult cell, was born on July 5, 1996. Since Dolly, many other sheep, mice, and calves have been cloned from differentiated adult cells.

A gene has two alleles, E and e. Another gene also has two alleles, T and t. Which of the following does NOT correctly show the linkage between the two genes?

Ee/tT

List the five major classes of developmental genes in Drosophila in the order (earliest to latest) that they regulate development.

Egg-polarity genes→gap genes→pair-rule genes→ segment-polarity genes→homeotic genes

nonstandard base pairings can occur as a result of the flexibility in DNA structure due to expose of UV light (True or False)

False

What characteristics of microsatellite markers make them useful in studying genetic variation?

Microsatellites are short DNA sequences that exist in multiple copies repeated in tandem. Variation in the number of copies of the repeats is common, with individual organisms often differing in the number of repeat copies.

Compare and contrast Mendel's principle of segregation and the principle of independent assortment.

Mendel's principle of segregation states that two alleles for each gene on HOMOLOGOUS chromosomes SEPARATE during gamate formation but the principle of independent assortment states that alleles on NON homologous chromosomes will independently separate from one another.

List and discuss two unique manners by which Angelman Syndrome may be transmitted (be very specific for full credit/give specific names).

My Answer: *Deletion*: inheriting a chromosome with a deletion from mom *Uniparental disomy*: inheriting two copies of the paternal UPD chromosome, and not the maternal one Professor's Answer: 1) uniparental disomy both chromosomes from dad(must say missing mom's contribution-take away 2 pt if they don't) 2) a deletion from the chromosome from the maternal chromosome (must say mother's contribution-take away 2 pt of they don't)

Which DNA strand forms Okazaki fragments during DNA replication (1pt)? Explain your answer in detail (1pt).

My Answer: The lagging strand! The leading strand goes in a 3' to 5' direction and therefore can replicate continuously. The lagging strand, however, synthesizes in the 5' to 3' direction discontinuously and is then connected with DNA ligase. Professor's Answer: DNA polymerase lays down nucleotides only adding 5' to 3' way but because the leading strand is antiparallel to the lagging strand, DNA is added continuously to the leading strand, and it is added discontinuously to the lagging strand, forming Okazaki fragments.

List and briefly discuss 3 different ways gene expression can be regulated in eukaryotic cells. Be very specific for full credit.

My Answer: 1. Chromatin shape allows specific genes to be relaxed and quickly transcribed, and others to remain tightly coiled and hidden 2. During RNA processing, alternate splicing lets individual cells express only certain portions of that strand of RNA (liver expressing liver genes for example) 3. Transcription factors are proteins that bind to DNA enhancers or silencers to turn specific genes on and off based on the environment and which genes the cell needs express; they can be called activators or repressors. Possible Answers: methylation of DNA RNAi post-translational modification acetylation of histones methylation of histones limiting machinery for transcription or translation

Traits encoded on mitochondria are generally inherited from:

Only the mother

Which Law would you use to answer the following question: What is the chance of flipping a coin and getting four heads in a row? (NOTE: H1 = heads on the first roll, H2 = heads on the second roll, etc.)

P(4 heads in a row) = P(H1) x P(H2) x P(H3) x P(H4)

What properly reflects the Law of Or?

P(E1 or E2) = P(E1) + P(E2)

Protein electrophoresis was the first molecular technique to measure genetic variation. However, this technique normally underestimates the true amount of genetic variation. Why?

Protein electrophoresis does not detect some amino acid substitutions, nor does it detect genetic variation in DNA that does not alter the amino acids of a protein (synonymous codons and variation in noncoding regions of the DNA).

Explain how retroviruses may cause cancers.

Retroviruses are RNA viruses that use reverse transcriptase to make a DNA copy that can integrate into the host chromosome. Retroviruses can (1) mutate host genes when inserted and (2) alter the expression of host genes (for example, by inserting promoters).

Which of the following is observed in prokaryotes but not in eukaryotes? a) In prokaryotes, ribosomes move along an mRNA in the 3' to 5' direction. b) UGG is an example of a stop codon only found in prokaryotes. c) An mRNA can be translated by only one ribosome at a time in prokaryotes. d) The 5' end of a prokaryotic mRNA can be translated while the 3′ end is still being transcribed.

The 5' end of a prokaryotic mRNA can be translated while the 3′ end is still being transcribed.

What is observed in prokaryotes but not in eukaryotes?

The 5' end of a prokaryotic mRNA can be translated while the 3′ end is still being transcribed.

The allele that causes achondroplasia is a recessive lethal allele

For most protein-encoding genes, the synonymous rate of change is considerably higher than the nonsynonymous rate. In comparing two taxa, how might you interpret the evolutionary history of a gene if the nonsynonymous rate of change was higher than the synonymous rate?

The expectation that the synonymous rate of change is higher than the nonsynonymous rate is based on the assumption that synonymous changes are tolerated by natural selection and nonsynonymous changes are eliminated by selection. If, however, those amino acid changes are beneficial to the organism, selection would lead to an increase in their frequencies. A nonsynonymous rate of change higher than the synonymous rate would imply positive selection on those changes.

The eyes of insects and mammals must have evolved independently during evolution.

What are the role and relationship of egg-polarity genes, segmentation genes, pair-rule genes, gap genes, and homeotic genes in Drosophila development?

The major axes and regions of the embryo are first established by egg-polarity genes. Next, distinct patterns within each of these large regions are determined by the action of segmentation genes (gap genes, pair-rule genes, and segment-polarity genes). The gap genes define large sections, the pair-rule genes define regional sections of the embryo and affect alternate segments, and the segment-polarity genes affect individual segments. Finally, the homeotic genes establish unique identities for each segment.

Compare and contrast Mendel's principle of segregation and the principle of independent assortment.

The principle of segregation involves segregation (separation) of the alleles of a gene pair as the paired homologs on which they reside separate during anaphase I of meiosis, This principle can be demonstrated using a single pair of homologous chromosomes The principle of independent assortment involves the random assortment of alleles from different homologs into separate daughter cells during meiosis I. This principle can only be demonstrated using two or more pairs of homologous chromosomes.

Honeybees have a haplo-diploid sex determination system where females develop from a fertilized egg (they are diploid, having one allele from the female queen and one allele from the male), and males develop from unfertilized eggs (they are haploid, having only one allele from the queen). Assuming that the queen is heterozygous for a particular gene, what is the probability that a female will inherit the recessive allele from her mother? What is the probability that a male will inherit a recessive allele from his mother?

The probability that a daughter will inherit a recessive allele from her mother is 50%; the probability that a son will inherit a recessive allele from his mother is 50%.

Give an example of a pair of independent events.

The probability that it will rain and the probability that you will have to mop muddy floors.

In a cross between pure-breeding tall plants with pure-breeding short plants, all of the F1 are tall. When these plants are allowed to fertilize themselves, the F2 plants occur in a ratio of 3 tall:1 short. Which of the following is not a valid conclusion from these results?

The tall and short traits assort independently of each other in this cross.

What is one line of evidence supporting the idea that cancer is influenced by environmental factors?

There are significant differences in the incidences of specific cancers around the world, and studies show that immigrants to a country will, over time, tend to exhibit the cancer incidence of their host country, regardless of differences in the cancer rate in their country of origin. Many students will surely answer this question with the association of cigarette smoking with lung cancer.

Which of the following codons does not stop translation? a) .UAG b) UAA c) UAU d) UGA

UAU

Why are viruses considered to be neither prokaryotic nor eukaryotic?

Viruses do not possess the structure of a cell. Viruses are actually simple structures composed of an outer protein coat surrounding nucleic acid. Viruses cannot reproduce outside of their host cells, suggesting that that viruses evolved after cells were present and not before.

Which of the following characterizes dynamic equilibrium? (Check as many as apply) There is no net change in the distribution of alleles. The forward and backward mutation rates must be zero. The number of forward and backward mutations must be equal. It always occurs in a single generation.

There is no net change in the distribution of alleles. The number of forward and backward mutations must be equal.

A ratio of 2:1 is observed when there is

a recessive lethal allele.

The microsatellite study of bighorn sheep described in Section 26.1 was a study of:

anagenesis

The process by which genetic changes occur in tumors and allows them to become increasingly aggressive over time is called

clonal evolution

Interactions among the human ABO blood group alleles involve _____ and _____.

codominance; complete dominance

As set of overlapping DNA fragments that form a contiguous stretch of DNA is called a

contig

What is the function of lactose in regulation of the lac operon?

It inactivates a repressor protein

What could explain how there could be two different syndromes from only one gene mutation at the same location on a specific allele?

epigenetics

A fly with genotype XXY would be phenotypically

female

Which statement is true with regards to the language of genetics?

triplets are the the linear sequence of nucleotide bases of DNA

The corepressor of tryptophan biosynthesis in the trp operon of E. coli is

tryptophan

How would an operon that can be activated and requires an activator protein be classified?

under positive inducible control

In human polydactyly some people have an entire extra finger while others only have a small nub on their hand. This difference in phenotype, even with the same genotype ic called

variable expressivity

In the Ames test, what types of mutations are used to test for chemical mutagens?

his- to his+ mutations

In a nucleosome, what is the DNA wrapped around?

histones

Which group of genes specifies the identities of individual body segments(parts)?

hox

You find an X ray machine that offers to measure your feet for the perfect shoe fit. Why should you refuse to use this machine?

it can cause breakage of your chromosomes

Of the various evolutionary forces, _________ is responsible for the origin of new genetic material.

mutation

Which of the following is NOT a common characteristic seen in pedigrees for a Y- linked trait?

often skips generations Things that ARE true: Passes from father to all sons Only males are affected

Interference occurs when

one crossover reduces the likelihood of another.

A testcross includes

one parent who shows the dominant phenotype for one or more genes and a second parent who is homozygous recessive for these genes.

The 5' cap and 3' poly A tail found in mRNA

play a role in initiation of translation

What does the Red Queen Hypothesis state?

proposes that organisms must constantly adapt, evolve, and proliferate in order to survive while pitted against ever-evolving opposing organisms (pathogens and predators)

What is the main function of meiosis?

reduce the chromosome number by half in gametes

Ribozymes may

regulate translation

What enzyme is used to create cDNA from mRNA?

reverse transcriptase

Humans do not have ______________ chromosomes

telocentric

Give an example of an event that is not mutually exclusive.

the chance that you will answer the ringing phone or take a walk.

Support for evolution is NOT found in

the change an organism undergoes as it ages.

Turner's syndrome is the only trisomy compatible with life

False

The haploid human genome contains about 3 × 109 nucleotides. On average, how many DNA fragments would be produced if this DNA was digested with restriction enzyme PstI (a 6-base cutter)? RsaI (a 4-base cutter)? How often would an 8-base cutter cleave?

(1) A 6-base cutter will cleave random-sequence DNA on average once every 46 = 4096 nucleotides. Therefore, on average there would be 3 × 109/4096 = 732,422 cleavage sites in this much DNA and thus 732,422 different fragments.(2) A 4-base cutter would cut, on average, once every 44 = 256 nucleotides. Therefore, you'd expect 3 × 109/256 = 11,718,750 different fragments.(3) An 8-base cutter would cut, on average, once every 48 = 65,536 nucleotides.

What three sets of proteins are required for immune responses?

(1) Antibodies (2) T-cell receptors (3) Major histocompatibility antigens

What is the difference between apoptosis and necrosis?

(1) Apoptosis is a form of programmed cell death that is usually initiated by the cell itself. Apoptosis is essential to development and embryogenesis in animal and plant cells. In fact, most multicellular animals cannot complete development if the apoptosis process is blocked. (2) Necrosis is the process of cells dying in an uncontrolled, unregulated manner after they are injured.

If a population is in Hardy-Weinberg equilibrium, the allelic and genotypic frequencies will not change. Prove the preceding statement for a pair of alleles in population X, which is in Hardy-Weinberg equilibrium.

(1) Determine the genotypic frequencies using the two alleles R and r. p^2 (RR) + 2pq (Rr) + q^2 (rr) = 1. Note that the total proportion of dominant R alleles in population X equals the sum of all the gametes produced by the RR homozygotes + half the gametes produced by the Rr heterozygotes, that is, p^2 (RR) + pq (Rr). (2) Calculate the frequency of R in the gene pool of the next generation. Note that the percentage of all the R and r alleles in the population is 100%. For these alleles (i.e., the alleles of interest), p + q = 1 (100%), and q = 1 - p. Therefore, p^2 (RR) + pq (Rr) = p^2 + p (1 - p) = p^2 + p - p^2 = p. Because the frequency of the dominant allele (R) remains constant in the next generation, it follows that neither the frequency of the recessive allele nor the frequencies of the relevant genotypes (RR, Rr, rr) will change in subsequent generations for population X. In other words, p^2 (RR) + 2pq (Rr) + q^2 (rr) = 1 = p + q.

How do incomplete penetrance and variable expressivity differ?

(1) If some individuals in a population don't express a trait, even though they have the corresponding genotype, the trait is said to exhibit incomplete penetrance in that population. When using the term penetrance , therefore, think of populations. Polydactyly (extra fingers and toes) exhibits incomplete penetrance in human populations. (2) A trait exhibiting variable expressivity is not expressed at the same degree among all individuals expressing it. Male pattern baldness in humans is an example of a trait that exhibits variable expressivity. Note: For incomplete penetrance, not everyone with the genotype will express the phenotype. For variable expressivity, everyone with the genotype expresses the phenotype to some degree. Of course, some traits may (and often do) exhibit both incomplete penetrance and variable expressivity.

What are some of the different signals that can initiate programmed cell death (apoptosis)?

(1) Pathogen infection by viruses and so forth can activate immune cells to secrete substances onto an infected cell, causing that cell to undergo apoptosis. This defensive measure would prevent spread of the pathogen in an organism. (2) DNA damage can activate apoptosis to prevent replication of mutated sequences. (3) Damage to mitochondria may cause the initiation of apoptosis. (4) Accumulation of misfolded proteins in the endoplasmic reticulum may signal the cell to undergo apoptosis.

Describe one major difference in the organization or content of prokaryotic and eukaryotic genomes.

(1) Prokaryotic genomes generally have less DNA and fewer genes than eukaryotic genomes.(2) Prokaryotic genomes have fewer repeated sequences and noncoding, intragenic sequences than eukaryotic genomes.(3) Most prokaryotic genomes are contained in one chromosome; most eukaryotic genomes are contained on several chromosomes.(4) The prokaryotic genome shows evidence of much horizontal gene transfer.(5) The eukaryotic genome shows evidence of much gene duplication.(6) In general, eukaryotic genomes contain many introns, repeated sequences, and transposable elements.

List three ways in which proto-oncogenes can be converted to oncogenes by viruses

(1) The sequence of the proto-oncogene may be altered or truncated when the proto- oncogene is incorporated into the viral genome. The mutated gene could then produce an aberrant protein product that triggers uncontrolled cell proliferation when the virus invades another cell. (2) Through recombination, a proto-oncogene may become juxtaposed next to a new promoter or enhancer, which can then cause the gene to be overexpressed. (3) The function of a proto-oncogene in the host cell may be altered when viral DNA inserts into the gene. The mutated gene could then produce an aberrant protein product that triggers uncontrolled cell proliferation.

Explain what an RFLP is. Why do RFLPs behave like markers?

(1)RFLPs (restriction fragment length polymorphisms) are molecular markers that are detected by virtue of the differences in their DNA sequence length. (2)RFLPs are DNA sequences, and thus their detection is not dependent upon expression of a protein or RNA product. Unless the entire region that hybridizes to a probe has been deleted (highly unlikely), all genome copies (e.g., two in a diploid) of an organism will contain some sequences that will anneal to the probe and be detected. At the genomic DNA level, there is no recessiveness or dominance because the DNA itself, rather than a gene product, is being detected by the probe.

(a) What is a molecular clock? (b) In what situation(s) would it be especially useful? (c) Explain how a molecular clock is calibrated. (d) What are some known problems with using molecular clocks?

(a) A molecular clock is the amount of change that a protein or DNA sequence has undergone during the evolution of two divergent species. If the rate of change is constant and known, the amount of change can be used to estimate the time since the divergence. (b) A molecular clock is most useful when the fossil record is incomplete and does not allow for an estimation of the time since divergence between two species. (c) The molecular clock can be calibrated by determining the number of differences in a protein or DNA sequence between species whose time since divergence is known from the fossil record. (d) Some studies show that molecular changes do not always occur at a constant rate or at the same rate within different lineages so that a calibration might not be valid for the species in question.

(a) In what sense does each person's immune system become adapted to that person's environment and to the set of antigens to which that person is exposed? (b) Explain in terms of the clonal selection theory how a person's immune system responds to and comes to be "adapted" to the person's environment and personal exposure to antigens.

(a) Each person's immune system normally is capable of making antibodies against virtually any antigen that might be encountered in the person's lifetime. So everyone normally starts with the same or similar complete immune response repertoire. However, each person's immune system normally only makes antibodies in significant quantities against the antigens to which the person is actually exposed. Also in many cases a person's immune system "remembers" the initial exposure and is able to mount a more effective defense against subsequent exposures, providing long-term immunity. Therefore, each person's immune system adapts itself uniquely to the set of antigens that it encounters.(b) The clonal selection theory states that, initially, there is a large pool of millions of different lymphocytes, each capable of responding to only one antigen so that millions of different antigens can be detected. When a lymphocyte encounters its specific antigen and binds to it, the lymphocyte is stimulated to proliferate rapidly, producing a large population of genetically identical descendant cells (a clone) that is able to produce a large quantity of the antibody that is specific to that particular antigen. Thus, the immune system normally only mounts an active defense against the antigens that it actually encounters. In many cases, some members of the selected clone, called memory cells, remain in circulation for a long time and provide lasting immunity to the pathogen that bears that particular antigen.

(a) What is horizontal gene transfer? (b) How does horizontal gene transfer generate incongruity between phylogenetic (species) trees and gene trees?

(a) Horizontal gene transfer is the transfer of genetic material from one species to another. It occurs commonly in nature between different species of bacteria but is thought to be rare between eukaryotic cells. (b) Horizontal gene transfer generates incongruities between species and gene trees because distantly related species can end up carrying very similar DNA fragments that have been transferred horizontally. The genes will appear close together on a gene tree even though the species in which they reside are far apart on a species tree.

a) What are pseudogenes? (b) Why might homologous pseudogenes in a group of closely related species be more useful than "real" genes for elucidating phylogenetic relationships between those species?

(a) Pseudogenes are nonfunctional genes that arise from duplication of a gene followed by one or more mutations that destroy the function of one copy. (b) Because pseudogenes are nonfunctional, they accumulate mutations freely and rapidly compared to functional genes. Therefore, one is more likely to find a suitable number of mutation events when comparing the sequences of homologous pseudogenes, even in closely related species. Furthermore, mutations in pseudogenes are selectively neutral, and analysis based on such mutations will not be confounded by natural selection.

Explain the process of DNA translation in eukaryotes. List and discuss the role of all important enzymes, discuss direction of synthesis.

*Activation*: The amino acid associated with the Start codon, methionine, is covalently bonded to a tRNA InitiationAssisted by initiation factors, the small subunit of a ribosome assembles itself on the 5' end of a strand of mRNA; a large subunit then comes and binds to the tRNA as well *Elongation*: The ribosome moves along the mRNA, attaching to the tRNAs that are connected to the corresponding amino acids. The tRNAs enter the ribosome at the A part, assemble the amino acid to the chain in the S part, and exit from the E part. *Termination*: When the ribosome reaches a STOP codon, the ribosome detaches itself and the polypeptide is severed from the last tRNA so it can fold into its tertiary structure

Transcription occurs along a _____ template forming an mRNA in the _____ direction.

3'-5'; 5'-3'

Name conditions necessary for evolution to occur.

-mutations -natural selection -the population is not infinitely large -only some the population breed -non-random mating -everyone does not produce the same number of offspring, meaning there is differential reproductive success

Assume both parents are ET/et, and the recombination frequency is 30%. What is the chance of a child having the Et/Et genotype?

.0225

How many Barr bodies would a Turner's Syndrome patient have?

If a female Drosophila that is heterozygous for a recessive X-linked mutation is crossed to a wild-type male, what proportion of female progeny will have the mutant phenotype?

Meselson and Stahl showed that DNA is replicated in a semiconservative fashion. If they started out with all DNA incubated in n14 that was 100% light, after two rounds of replication in an N15 (heavy) medium, what fraction of the DNA would be light (all n14) after this second round of replication?

Suppose that extra fingers and toes are caused by a recessive trait, but it appears in only 60% of homozygous recessive individuals. Two heterozygotes conceive a child. What is the probability that this child will have extra fingers and toes?

0.15

If the frequency of aa genotype is 0.16, the frequency of Aa genotype is 0.48, and the frequency of AA genotype is 0.36 what are the frequencies of the A and a alleles?

0.6, 0.4

There is a gene that causes people to have crumbly earwax. This gene is expressed as a complete dominant: Individuals who are homozygous dominants (CC) or heterozygous (Cc) have crumbly earwax. Homozygous recessives (cc) have gooey earwax. There are 100 people, 64 of whom have crumbly earwax. Assuming Hardy-Weinberg conditions, what is the frequency of the c allele on Paradise Island?

0.60

What is the allelic frequency of A for the following population: Genotype ----------------AA----Aa----aa Number of individuals --450---300---150

0.667

List at least two processes involved in apoptosis that are controlled by caspases.

1) Caspase activity results in the cleavage of proteins that are essential to cell function, such as actin and other proteins that support the nuclear membrane and cytoskeleton. As a consequence, cells undergoing apoptosis lose their shape. (2) Caspases also cleave a regulatory protein that normally functions to maintain an enzyme that degrades DNA (i.e., DNase) in an inactive form. Cleavage of this regulatory protein releases DNase from inhibition and thereby activates it, resulting in subsequent breakdown of cellular DNA, which eventually leads to cell death.

You are studying the population in Iceland for X-linked alleles, and sampling experiments indicate that 6% of the men have red-green color blindness (caused by a recessive, X-linked allele c). Assume that the population in Iceland mates randomly. show all work you will lose points for not showing your work 1. What are the q frequencies for the c allele and p frequency for the C allele? (2 pts) 2. What percentage of women have normal vision? (2pts) 3. What percentage of women are expected to be color blind? (2 pts) 4. What percentage of females are carriers for the color-blind allele? (2 pt) 5. What percentage of men are carriers? (2pt)

1) What are the q frequencies for the c allele and p frequency for the C allele? .06=q for x linked in males p=.94 2) What percentage of women have normal vision? This is all p^2 and 2pq P^2 (.94)^2= 0.8836 + 2(0.06)(0.94) = 0.1124 = normal vision =0.996 3) What percentage of women are expected to be color blind?Q^2=(0.06)2 =0.0036 = 0.36% 4) What percentage of females are carriers for the color-blind allele?2pq= 2(0.06)(0.94)=11.2% 5) What percentage of men are carriers? None, men are hemizygous

Describe two different ways Retinoblastoma may develop?

1) one cell undergoes two Rb somatic mutations independently in the same cell 2) a predisposed person inherits Rb one mutation, then some cells undergo one somatic mutation, producing to Rb cancer (in this case, higher likelihood of occurring twice)

Why might bacteria and viruses be good model organisms for studying the basics of inheritance? Describe two advantages over studying genetics in mice, dogs, or humans

1. Bacteria and viruses have their genetic material (DNA) organized into genes, just like other organisms, so the basics of inheritance are the same in bacteria and viruses as in other organisms. 2. The genetic systems of bacteria and viruses are simpler when compared to higher eukaryotic organisms such as mice, dogs, or humans: they have fewer genes, fewer chromosomes, and less DNA. 3. Bacteria and viruses reproduce more quickly than higher eukaryotic organisms: the generation time is shorter than for mice, dogs, or humans. 4. Bacteria and viruses are easy and less expensive to grow (take up less space, have less complicated nutritional needs) than vertebrates.

List and briefly describe three major cell cycle checkpoints. For each checkpoint, predict the consequences if the checkpoint fails to work properly.

1. The G1/S checkpoint holds the cell in G 1 until the cell has all of the enzymes necessary for replication of DNA. If the checkpoint failed, the cell would proceed into S without the necessary enzymes, causing the DNA not to be replicated properly or completely. This might cause the cell cycle to halt at the G2/M checkpoint. Alternatively, the cell might divide without the genetic material having been replicated, causing the daughter cells to receive incomplete genetic information. 2. The G2/M checkpoint is passed only if the cell's DNA is undamaged.If it fails to work properly, division would proceed in the presence of damaged DNA, possibly leading to mutations in the daughter cells and/or death of the daughter cells. 3.. The spindle-assembly checkpoint is during metaphase, and it ensures that each chromosome is aligned at the metaphase plate and attached to spindle fibers from opposite poles. This checkpoint depends on tension at the kinetochores of each chromosome. If the checkpoint fails, anaphase will occur even when the chromosomes are not aligned properly, allowing daughter cells to be produced with extra and/or missing chromosomes.

The genes for flower color - G=gold, g=silver and the genes for flower shape R=round, r=oblong will be examined through various crosses. See below. Parental: two true breeding parents are crossed (GGRR x ggrr) Below are the results of a testcross performed with the F1 generation. A) What was your calculated chi squared value (1 pt) and what is the Chi squared table value (.5)? B) State the null hypothesis (.5)and whether you accept or reject your null hypothesis (1pt). Genotype Number of Individuals GgRr: 111 Ggrr: 134 ggRr: 121 ggrr: 119

1. remember there are two classes: parental and recombinant so df is 2-1=1 df chi table value = 3.84 2. calculated = 2.24 3. null: no linkage / genes assort independently / offspring fits 1:1:1:1 ratio for a testcross 4. accept the null

If in humans, brown eyes are dominant over green eyes, and two heterozygous parents have three children, what is the probability that all of the kids will have green eyes?

1.5%

In animals, the inability to make the pigment melanin results in albinism, a recessive condition. Two unaffected parents, who have decided to have three children, have a first child that has albinism (genotype aa). What is the probability that both the second and third children will also have albinism?

1/16

Suppose that some cells are grown in culture in the presence of radioactive nucleotides for many generations so that both strands of every DNA molecule include radioactive nucleotides. The cells are then harvested and placed in new medium with nucleotides that are not radioactive so that newly synthesized DNA will not be radioactive. What proportion of DNA molecules will contain any radioactivity after two rounds of replication?

1/2

A woman wants 5 children. She is pregnant with her 4th child and already has 3 children who are females. What is the probability her 4th and 5th children will also be females?

1/4

Two gene loci, A and B, assort independently, and alleles A and B are dominant over alleles a and b. What is the probability of producing an AB gamete from an AaBb individual?

1/4

In humans, tay-sachs is a metabolic disease that is caused by a recessive allele. What is the probability that two parents, heterozygous for the trait, will have three children who will be carriers for the disease?

1/8

The mosquito Aedes aegypti has a diploid number of 10 chromosomes. How many DNA molecules and Chromosomes are found per cell when this cell is progressing through the following stages: After Anaphase II of Meiosis the cell has ___ DNA molecules and ___ Chromosomes

10, 10

Crossing two yellow mice results in 2/3 yellow offspring and 1/3 nonyellow offspring. What percentage of offspring would you expect to be nonyellow if you crossed two nonyellow mice?

100%

Two true breeding stocks of fruit flies are crossed. One parent had red, oval eyes and the other had white, round eyes; all F1 individuals had red, oval eyes. If 1,000 F2 offspring resulted from the cross, how many of them would you expect to have red, round eyes? (Assume independent assortment.)

189

How many Barr bodies would an XXX female have?

How many phenotypes result from a dihybrid cross involving completely linked genes (i.e., no crossover)?

What is the theoretical minimum number of different tRNAs required by a cell?

20 - one for each amino acid

If a DNA molecule is 30% cytosine (C), what is the percentage of thymine (T)?

20%

Phenylketoneuria (PKU) is a recessive condition. There are 40,000 individuals in a population of 100,000 that have the disease. What are the total number of alleles in the population?

200,000

25%

The presence of horns in a certain breed of sheep is due to a sex-influenced trait with horns being dominant in males and recessive in females. A hornless male is bred with a horned female. The F1 generation are then crossed. What fraction of the F2 females is expected to have horns?

25%

In a cross between AaBb and AaBb, what proportion of the offspring would be expected to be A_bb?

3/16

If the probability that a plant will release seeds is 75%, the probability that a given seed will germinate is 50%, and the probability that a germinating plant will be eaten by a deer before it matures is 20%, what is the probability that a parent will see its progeny survive to adulthood?

30%

All DNA polymerases synthesize new DNA by adding nucleotides to the _____ of the growing DNA chain.

3′ OH

A diploid somatic cell from a rat has a total of 42 chromosomes (2n = 42). What is the total number of chromosomes present in the cell during metaphase I of meiosis?

You roll two dice (each die has six sides). What is the probability that you won't roll a 1 or a 6 on either die?

44.4%

Suppose a population of 1000 people is in H-W equilibrium, if 84% of this population can taste PTC, how many are heterozygotes, considering that ability to taste PTC is inherited as a dominant allele?

480

If a tRNA sequence is 5' GGC 3', what is the corresponding DNA sequence on the template strand?

5' GGC 3' *tRNA is the same as template strand of DNA*

Interactions among the human ABO blood group alleles involve _____ and _____. A) codominance; complete dominance B) codominance; incomplete dominance C) complete dominance; incomplete dominance D) epistasis; complementation E) continuous variation; environmental variation

Among the model genetic organisms, Escherichia coli, a single-celled bacterium, is a prokaryote; Saccharomyces cerevisiae, one-celled yeast, is a eukaryote, as are Caenorhabditis elegans, a multicellular nematode worm, and Arabidopisis thaliana, a multicellular plant. Which of these organisms would NOT contain membrane-bound organelles? A) Escherichia coli B) Saccharomyces cerevisiae C) Escherichia coli and Saccharomyces cerevisiae D) Caenorhabditis elegans E) Caenorhabditis elegans and Arabidopisis thaliana

Consider the Ras signal-transduction pathway. Suppose that a mutation occurred within the gene that encodes the transmembrane receptor protein. Which of the following types of mutations in this receptor could lead to cancer? A) a mutation that allows the receptor to become phosphorylated in the absence of a growth factor bound to it B) a mutation in the extracellular domain that prevents the binding of a growth factor C) a mutation in the transmembrane domain that prevents the signal from being transduced to the interior of the cell D) a mutation within the intracellular domain that prevents interaction with the adaptor molecules E) All of these are types of receptors mutations that could lead to cancer.

Evidence that the development of cancer is a multistep process includes the: A) observation that certain tumor-suppressor genes and oncogenes are involved in a sequential manner in the development of colon cancer B) fact that proto-oncogenes are widely conserved in evolution C) usual occurrence of retinoblastoma at a young age D) development of a cancer as a result of activation of a single oncogene by any of a variety of mechanisms E) fact that there are many genetic and epigenetic mechanisms that lead to inactivation of the same tumor-suppressor gene

Genes come in different versions called: A) alleles. B) loci. C) genotypes. D) chromosomes. E) genomes.

Gregor Mendel carried out a cross between two pea plants by taking pollen from a plant that was homozygous for round seeds and dusting the pollen onto the stigma of a plant homozygous for wrinkled seeds. Which of the following would be the reciprocal cross that Mendel had carried out for this experiment? A) Stigma of a plant homozygous for round seed pollinated with pollen from a plant homozygous for wrinkled-seed plant B) Stigma of a plant homozygous for round seed pollinated with pollen from a plant heterozygous for wrinkled-seed plant C) Stigma of a plant heterozygous for round seed pollinated with pollen from a plant homozygous for wrinkled-seed plant D) Stigma of a plant homozygous for wrinkled seed pollinated with pollen from a plant homozygous for round-seed plant E) Stigma of a plant homozygous for wrinkled seed pollinated with pollen from a plant homozygous for wrinkled-seed plant

In a cross between AaBbCcDdEe and AaBbccDdee, what proportion of the offspring would be expected to be A_bbC_ddE_? (A_ means AA or Aa.) A) 3/256 B) 3/32 C) 3/16 D) 3/8 E) 3/4

In eukaryotes, chromosomes do NOT contain: A) ribosomes. B) chromatin. C) proteins. D) histones. E) DNA.

In species of birds, males are the homogametic sex and females the heterogametic sex. Which of the following statements is TRUE in this system of sex determination? A) The gender of the offspring is determined by the female parent. B) Male offspring have a ZW chromosome constitution. C) The gender of the offspring is determined by the male parent. D) Female offspring have a ZZ chromosome constitution. E) Female and male offspring have the same chromosome constitution

Many tumors exhibit: A) abnormally high levels of telomerase expression. B) abnormally high levels of tumor-suppressor gene expression. C) translocations that move a tumor-suppressor gene to a new location that increases its normal expression. D) deletions that remove an oncogene from the genome. E) DNA replication that is inhibited when it would normally occur.

Normal cellular genes whose products are involved in facilitating cell division to occur under appropriate conditions are called: A) proto-oncogenes. B) tumor-suppressor genes. C) passenger genes. D) inhibitor genes. E) driver genes

Polydactyly is the condition of having extra fingers or toes. Some polydactylous persons possess extra fingers or toes that are fully functional, whereas others possess only a small tag of extra skin. This is an example of: A) variable expressivity. B) complete dominance. C) independent assortment. D) complementation. E) cytoplasmic inheritance.

The eyeless gene in fruit flies, Pax6 gene in mice, and Aniridia gene in humans are orthologs. Mutations in these genes result in defects in eye development for each species. Which of the following statement is NOT consistent with this observation? A) The eyes of insects and mammals must have evolved independently during evolution. B) The same genes in distantly related organisms can shape similar developmental pathways. C) A common pathway underlies eye development in all three organisms. D) All three genes evolved from a common ancestral sequence.

The golden mutation in the zebrafish was useful because of which of the following results? A) It led to the discovery of a similar gene in humans that is involved in skin pigmentation. B) It led to the development of new varieties of wheat. C) It led to the ability to identify many of the genes that result in an increase in heart attacks. D) It allowed the zebrafish to be grown in captivity and become commercially profitable. E) It became the first gene in a model organism to be sequenced.

The insect hormone ecdysone is known to trigger apoptosis during metamorphosis that turns larva into adult structures. Which of the following experiments would confirm the activation of apoptosis by ecdysone? A) Inhibition of rpg and hid gene via RNAi should result in excess cells that would normally be eliminated. B) Overproduction of rpg and hid genes via constitutive promoter should prevent the full metamorphosis. C) Inhibition of receptor binding to ecdysone should result in excess apoptosis. D) Overproduction of ecdysone receptor should result in inhibition of rpg and hid genes. E) Inactivation of grim should result in elimination of excess number of cells.

The process of splitting the cytoplasm, which separates one cell into two, is termed: A) cytokinesis. B) mitosis. C) anaphase. D) diakinesis. E) fusion.

The sex determination system used by Drosophila is called: A) the X:A sex determination system. B) the ZZ-ZW sex determination system. C) the XX-XO sex determination system. D) the XX-XY sex determination system. E) genic sex detemination.

Which of the following human genotypes is associated with Klinefelter syndrome? A) XXY B) XYY C) XXX D) XO E) XX

Which of the following statements is FALSE? A)Errors in chromosome separation are rarely a problem for an organism. B)Errors in chromosome separation can result in a miscarriage. C)Errors in chromosome separation can result in cancer. D)Errors in chromosome separation can result in a child with severe handicaps. E)Errors in chromosome separation can cause numerous problems for an organism.

Which one of the following topics of research belongs to the discipline of transmission genetics? A) inheritance pattern of gene alleles B) mechanism of DNA replication C) gene expression patterns D) evolution E) chemical modification of nucleic acids

Distinguish between the genetic mechanisms used to generate antibody diversity within a person's immune system and those used to generate MHC antigen diversity between different individuals.

A huge diversity of antibodies is produced from a small number of genes through mechanisms that include somatic recombination, segment joining (junctional diversity), and somatic hypermutation. Somatic recombination produces many different light and heavy chains by bringing together various combinations of V segments to form the polypeptide- encoding genes. Segment joining is imprecise, and a few random nucleotides are frequently lost or gained at the junctions of the recombining segments, generating junctional diversity. Somatic hypermutation is a mechanism that causes an unusually high rate of mutations in antibody-encoding genes, generating even more diversity. Finally, a large number of combinations of different light and heavy chains are possible. Because of these mechanisms, a person's immune system is capable of making antibodies against virtually any antigen that the person might encounter. The diversity of MHC antigens between individuals is also impressive, but the mechanism by which this diversity is generated is quite different. This diversity is based on the number of antigen-encoding loci (at least five) and the large number of alleles at each locus (as high as 100). Because of the number of loci and the large number of alleles, no two individuals (except identical twins) would be expected to have the same set of histocompatibility antigens.

Distinguish between the genetic mechanisms used to generate antibody diversity within a person's immune system and those used to generate MHC antigen diversity between different individuals.

A huge diversity of antibodies is produced from a small number of genes through mechanisms that include somatic recombination, segment joining (junctional diversity), and somatic hypermutation. Somatic recombination produces many different light and heavy chains by bringing together various combinations of V segments to form the polypeptide-encoding genes. Segment joining is imprecise, and a few random nucleotides are frequently lost or gained at the junctions of the recombining segments, generating junctional diversity. Somatic hypermutation is a mechanism that causes an unusually high rate of mutations in antibody-encoding genes, generating even more diversity. Finally, a large number of combinations of different light and heavy chains are possible. Because of these mechanisms, a person's immune system is capable of making antibodies against virtually any antigen that the person might encounter.The diversity of MHC antigens between individuals is also impressive, but the mechanism by which this diversity is generated is quite different. This diversity is based on the number of antigen-encoding loci (at least five) and the large number of alleles at each locus (as high as 100). Because of the number of loci and the large number of alleles, no two individuals (except identical twins) would be expected to have the same set of histocompatibility antigens.

Cleft palate is a birth defect in which the two sides of the roof of the mouth do not fuse before birth. Cleft palate is considered to be a threshold trait. Define "threshold trait" and explain how cleft palate is an example of one.

A threshold trait is a multifactorial trait that has two phenotypes: present or absent. Multiple genes and environmental effects contribute to the development of the trait. If inherited and environmental factors combine to cross a "threshold," the trait is expressed.Babies are born either with cleft palate or with normal palate, so there are only two phenotypes. Inherited factors and events in development combine to determine whether the trait develops or not.

Transduction

A virus carries genes from one bacterium to another

Eye color has a concordance of 0.99 in monozygotic twins. What does this say about this trait? A) Most identical twins will have the same eye color B) Most fraternal twins will have the same eye color C) The environment plays a large role in the expression of eye color D) Eye color has a strong genetic component

A&D

Human blood type is determined by three alleles IA, IB, and IO. The alleles IA and IB are co-dominant to each other, and both are dominant to IO. Within a large, randomly mating population (540,000 individuals), the frequencies for the blood type alleles are 0.3 for the IA allele, 0.6 for the IO allele, and 0.1 for the IB allele. Calculate the expected numbers of people in the population having each of the blood types A, B, AB, and O. *A*) A = 243,000 people, B = 70,200 people, AB = 32,400 people, and O = 194,400 people *B*) A = 162,000 people, B = 54,000 people, AB = 3,240 people, and O = 324,000 people *C*) A = 48,600 people, B = 5,400 people, AB = 32,400 people, and O = 194,400 people *D*) A = 194,400 people, B = 64,800 people, AB = 32,400 people, and O = 194,400 people *E*) A = 243,000 people, B = 5,400 people, AB = 32,400 people, and O = 194,400 people

A) A = 243,000 people, B = 70,200 people, AB = 32,400 people, and O = 194,400 people

_____ occurs when one allele or trait is favored over another. A) Directional selection B) Mutation-selection equilibrium C) Founder effects D) Stabilizing selection E) Overdominance

A) Directional selection

Support for evolution IS found in

A) comparative anatomy. B) the fossil record. C) the distributions of species (biogeography). D) direct observation such as the evolution of pesticide resistance.

The relatively small amount of genetic differentiation among some species suggests that many phenotypic differences reflect changes in _____, rather than the evolution of new genes. A) gene expression B) gene duplication C) exon shuffling D) whole-genome duplication E) horizontal gene transfer

A) gene expression

A Mendelian population is defined by individuals that are: A) interbreeding. B) inbreeding. C) evolving. D) segregating. E) migrating.

A) interbreeding.

The evolutionary force of _____ tends to increase genetic variation within a population but decrease genetic variation between populations, while the evolutionary force of _____ tends to decrease genetic variation within a population but increase genetic variation among populations. A) migration; genetic drift B) mutation; some types of natural selection C) genetic drift; migration D) some types of natural selection; mutation E) positive assortative mating; negative assortative mating

A) migration; genetic drift

In humans, blood types A and B are codominant to each other and each is dominant to O. What blood types are possible among the offspring of a couple of blood types AB and A? (assume normal HH genotype for both parents)

A, B, AB

The fruit fly Drosophila melanogaster is an important model system for studying inheritance in animals and genetic control of animal development, including humans. If researchers ultimately want to understand a biological process in humans, why might they want to study the process in fruit flies first? (Select all that apply.) A) Fruit flies are relatively easy to genetically manipulate and to isolate mutations. B) Fruit flies have short generation times and produce relatively large numbers of progeny. C) Fruit flies have simpler genomes than do humans. D) Fruit flies share all important physiological and developmental processes with humans. E) Fruit flies are small and easy to raise

A,B,C,E

Which of the following traits would make a species useful as a model genetic organism? (Select all that apply.) A) large number of progeny B) long generation time C) small size D) ability to be studied in a laboratory E) ability to be propagated inexpensively

A,C,D,E

You have discovered a gene that enables organisms to accumulate gold in their tissues by concentrating trace amounts found in normal soil. You want to transfer this gene into a plant. Order the steps below that would accomplish this goal.1. Infect the plant with the Agrobacterium strain.2. Digest the gold gene and a Ti plasmid with appropriate restriction enzymes.3. Insert the gold gene into the Ti plasmid.4. Amplify the gold gene with PCR.5. Transfer the recombinant Ti plasmid into Agrobacterium tumefaciens.6. Use a selectable marker to identify plant cells that have integrated the recombinant plasmid into their genome. A.4, 2, 3, 5, 1, 6 B.4, 5, 2, 3, 1, 6 C.4, 2, 5, 1, 6, 3 D.4, 3, 2, 5, 1, 6

A. 4, 2, 3, 5, 1, 6

Which of the following traits of type I restriction enzymes make them unsuitable for recombinant DNA technology? (Select all that apply.) A. They are large, multi-subunit enzymes. B. They make double-stranded cuts in DNA. C. They cleave and methylate DNA. D. They cleave at sequences far from their recognition site. E. They were discovered in bacteria.

A. They are large, multi-subunit enzymes. C. They cleave and methylate DNA. D. They cleave at sequences far from their recognition site.

Southern blotting is a technique used to transfer _____ to a solid Moderate. A.DNA B.RNA C.protein D.DNA and RNA E.DNA, RNA, or protein

A.DNA

In mass spectrometry, a molecule is ionized and its migration rate in an electrical field is determined. What information does the migration rate tell about the molecule? A.It indicates mass because small molecules migrate more rapidly than larger molecules. B.It indicates electrical charge because negatively charged molecules migrate more rapidly than positively charged molecules. C.It indicates the solubility of the molecule because insoluble molecules form aggregates and migrate much more slowly than soluble molecules. D.It indicates the relative abundance of the molecule in the sample. E.It indicates the complexity of the proteome because greater proteome diversity takes a longer time to process.

A.It indicates mass because small molecules migrate more rapidly than larger molecules.

Crossing over is often reduced around centromeric regions of chromosomes. If you were trying to construct a genetic map of two linked marker loci in this region, how would the genetic map correspond to the physical map? A.The genetic map will underestimate the distance between markers because the low recombination rate will suggest that the markers are very close to one another when they could be physically far apart. B.The genetic map will underestimate the distance between markers because the markers will segregate independently in meiosis. C.The genetic map will overestimate the distance between markers because the low recombination rate will make it appear that they are far from one another when they could be physically close to one another. D.The genetic map will overestimate the distance between markers because rates of crossing over are not the same at all places on all chromosomes. E.The genetic and physical maps will precisely correspond since recombination rates at the centromere are lower and more predictable.

A.The genetic map will underestimate the distance between markers because the low recombination rate will suggest that the markers are very close to one another when they could be physically far apart.

Crossing over is often reduced around centromeric regions of chromosomes. If you were trying to construct a genetic map of two linked marker loci in this region, what result might you obtain? A.The recombination frequencies would be low, and you would deduce that the markers were very close to one another. B.The recombination frequencies would be low, and you would deduce that the markers were very far from one another. C.The recombination frequencies would be high, and you would deduce that the markers were very close to one another. D.The recombination frequencies would be high, and you would deduce that the markers were very far from one another. E.The recombination frequencies would be too low to detect, and you would not be able to estimate the distance between genetic markers.

A.The recombination frequencies would be low, and you would deduce that the markers were very close to one another.

The difference between PCR and real-time PCR is that real-time PCR: A.can measure the amount of DNA amplified as the reaction proceeds, while standard PCR cannot. B.can amplify DNA a billion-fold within just a few hours, while standard PCR cannot. C.can determine the DNA sequence, while standard PCR cannot. D.uses DNA polymerase, while standard PCR does not. E.requires primers, while standard PCR does not.

A.can measure the amount of DNA amplified as the reaction proceeds, while standard PCR cannot.

Two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) is a technique wherein proteins are separated in one dimension by a chemical property and in a second dimension by a different property. By what property are proteins separated in the first dimension? A.electrical charge B.molecular mass C.posttranslational modification D.isotope E.hydrophobic index

A.electrical charge

Loci that are far apart: A.have a higher recombination rate than loci that are close together. B.exhibit a recombination frequency of greater than 50%. C.always segregate together in meiosis. D.influence the phenotype to a lesser degree than loci that are close together. E.have less attraction than close loci.

A.have a higher recombination rate than loci that are close together.

Flower diameter in sunflowers is a quantitative trait. A plant with 6-cm flowers, from a highly inbred strain, is crossed to a plant with 30-cm flowers, also from a highly inbred strain. The F1 have 18-cm flowers. F1 × F1 crosses yield F2 plants with flowers ranging from 6 to 30 cm in diameter, in approximately 4-cm intervals (6, 10, 14, 18, 22, 26, 30). The number of different genes influencing flower diameter in this plant is: A.three. B.four. C.five. D.six. E.seven.

A.three.

Albinos occupy a privileged position among the Hopis of Black Mesa. In this culture, albinos are viewed as especially pretty, clean, and intelligent, and they often occupy positions of leadership. Albinos are celebrated in the villages as a sign of purity of Hopi blood in the community. Furthermore, albinos are often excused from normal male field labor because of their sensitivity to sunlight, causing them to be left behind in the village with the women during the daytime. This allows them extra mating opportunities compared to the other men of the village. Therefore, the alleles that cause albinism are either selected for in this culture or at least not selected against as strongly as in other cultures, allowing the trait to occur at a much higher frequency.

Which of the following statements is incorrect concerning an X-linked recessive trait in humans? An affected man usually has a mother who carries the recessive allele. An affected woman almost always has an affected mother. A phenotypically normal woman whose father was affected is likely to be heterozygous for the condition. All the sons of an affected woman will be expected to be affected An affected man often has phenotypically normal parents.

An affected woman almost always has an affected mother.

What is an autoimmune disease?

An autoimmune disease is a disease of the immune system whereby the body's ability to make a distinction between "self" and "nonself" is compromised so that an immune reaction is initiated against antigens present on the body's own cells. An example of an autoimmune disease is rheumatoid arthritis.

In a natural population of outbreeding plants, the variance of the total number of seeds per plant is 16. From the natural population, 20 plants are taken into the laboratory and developed into separate true-breeding lines by self-fertilization—with selection for high, low, or moderate number of seeds—for 10 generations. The average variance in the tenth generation in each of the 20 sets is about equal and averages 5.8 across all the sets. Estimate the broad-sense heritability for seed number in this population.

An estimate of VP is the variance in seed number in the natural population, or 16. An estimate of VE is the variance in the population in the true-breeding, inbred population, which is presumably homozygous for genes that affect seed number.VG = VP - VEH2 = VG/VP = (16 - 5.8)/16 = 0.64

You and a close friend from the University of Tennessee go hiking in the mountains. You are surprised to see a salamander that is bright orange in color. Thinking that some overzealous Tennessee fans have painted this particular amphibian, you walk on. As you continue your hike, you find other salamanders of this species and note that there is variation in the coloration: some individuals are bright orange, but others are drab in color. You also note that these salamanders often eat bright orange insects. How might you explain the presence of the color polymorphism in this salamander species?

An obvious hypothesis is that the variation comes from the fact that there is variation in what salamanders eat. This would imply that the variance is totally environmental: The orange salamanders ate orange bugs and turned orange. You can test to see if the coloration is environmental by doing a common garden experiment in which you feed an experimental group of salamanders the orange bugs and see if they all turn orange (an environmental effect). If they do not, at least some of the coloration variation is due to genetics.

How do lymphocytes violate the general principle that all cells in an organism contain the same set of genetic information?

Antibody genes in lymphocytes are organized in segments, and germ-line DNA contains different versions (alleles) of each of these segments. During lymphocyte maturation, gene rearrangements occur (through somatic recombination within a single chromosome), generating many different combinations of the different segments (V, D, and J), which results in the immense variety of different antibodies capable of being produced in the lymphocyte pool. Other contributing factors to this diversity are (i) the random association of light and heavy chains in different combinations, (ii) the random addition and deletion of nucleotides at the junctions of the segments during lymphocyte maturation, and (iii) the high mutation rate in immunological genes.

A genetics student recently learned of the connection between telomerase and cancer. Curious as to whether he is at risk for developing cancer, he sneaks into a lab at night to analyze his DNA. He isolates DNA from his skin cells and applies PCR using primers specific to the telomerase gene. He runs a gel on his PCR reaction and sees that he has a PCR product on the gel. He is terrified because he knows this means he has the telomerase gene in his skin cells and thinks he will develop skin cancer. He takes his findings to his genetics professor. What does she tell him (besides he shouldn't be sneaking into a lab!)? ' A) The telomerase gene should not be present in somatic cells; thus, he is at an increased risk of developing skin cancer and should take the results to his physician. B) His results are normal because the telomerase gene should be present in all cells, including somatic cells. However, its expression should only be found in stem cells and germ cells. He should have looked at the expression levels of the gene, not the presence of the gene itself (and he should study more!). C) His results are inconclusive because they cannot determine if the telomerase gene he amplified has a mutation in its coding sequence, which is what leads to cancer. D) Telomerase mutations that result in cancer behave in a dominant manner. Therefore, rather than going through the effort of a genetic analysis, the student should have constructed a family pedigree to determine if members of his family had skin cancer, which could then determine his risk. E) He should not be concerned about his cancer risk because transcriptionally active telomerase should be present in somatic cells to maintain the length of the chromosomes and thus prevent cancer.

CRISPR/Cas9 is a powerful new method that allows: A) DNA sequencing to be done very quickly so that numerous individual genomes can be sequenced in a short period of time. B) precise editing of specific DNA sequences in living cells. C) the identification of genes involved in important medical conditions. D) the introduction of genes from one species into another species. E) the arrangement of genes on chromosomes.

Epigenetic changes in development are important in that the gene expression of cells that make up a particular organ or tissue type is often defined by epigenetic markers. Which of the following epigenetic regulations is known to cause more long-term gene silencing during the course of development? A) chromatin remodeling B) DNA methylation C) histone modifications D) DNA ubiquitination

In a germ-line cell from a female grasshopper (XX-XO sex determination system), when do the homologous X chromosomes segregate? A) during mitosis B) during meiosis I, anaphase C) during meiosis II, anaphase D) They do not segregate; gametes contain a copy of X and a copy of Y. E) just before meiosis begins

In humans, blood types A and B are codominant to each other and each is dominant to O. What blood types are possible among the offspring of a couple of blood types AB and A? A) A, B, AB, and O B) A, B, and AB only C) A and B only D) A, B, and O only E) A and AB only

In prokaryotes, replication usually begins at a specific place on the chromosome called the: A) binary fission site. B) origin of replication. C) origin of mitosis. D) anchoring site. E) kinetochore.

Round seeds (R) are dominant to wrinkled seeds (r), and yellow seeds (Y) are dominant to green seeds (y). A true-breeding pea plant with round and yellow seeds is crossed to a truebreeding plant with wrinkled and green seeds. The F1 progeny are allowed to self-fertilize. What is the probability of obtaining a wrinkled, green seed in the F2? A) 3/4 B) 1/16 C) 9/16 D) 3/16 E) 1/2

The attachment point on the chromosome for spindle microtubules is the: A) telomere. B) centromere. C) origin of replication. D) sister chromatid. E) allele.

The cells of a mature pea plant have 14 chromosomes. In a pea plant ovary, how many chromosomes would the nucleus of a megaspore contain? A) 31/2 B) 7 C) 14 D) 21 E) 30

The eyeless gene in fruit flies, Small eye gene in mice, and Aniridia gene in humans have high homology in DNA sequence and their mutations result in defects in eye development. Which of the following statements is NOT consistent with this observation? A) The same genes in distantly related organisms can shape similar developmental pathways. B) The eyes of insects and mammals must have evolved independently during evolution. C) A common pathway underlies eye development in all three organisms. D) All three genes evolved from a common ancestral sequence.

What is the expected outcome for a human embryo with the XXXY chromosome constitution? A) It would likely develop into a female who will not respond to the hormone testosterone. B) It would likely develop into a sterile male with reduced testes. C) It will always abort early in development before birth. D) It would likely develop into a tall female who may be slightly cognitively impaired. E) It would likely develop into a fertile man with a completely normal male phenotype.

Which cell cycle checkpoint is most responsible for the decision of the cell to commit to dividing? A) the S/G2 checkpoint B) the G1/S checkpoint C) the spindle-assembly checkpoint D) the G2/M checkpoint E) the G1/G2 checkpoint

Which of the following are regulatory molecules whose normal function is to inhibit gene expression but which often have reduced activity in many tumor cells? A) histones B) miRNAs C) reverse transcriptases D) growth factors E) kinases

Which of the following is the major event associated with the retinoblastoma cancer? A) a translocation involving chromosomes 9 and 22 B) both copies of a tumor-suppressor gene being inactivated C) a translocation resulting in the enhanced expression of an oncogene D) a mutation resulting in an activated RAS oncogene E) inactivation of a major DNA repair system

Which of the following processes is unique to plants? A) meiosis B) double fertilization C) crossing over D) haploid gametes E) spermatogenesis

Which of the following result(s) directly from metastasis? A) primary tumors B) secondary tumors C) tumor vascularization D) decreased DNA repair E) increased apoptosis

Which of the following statements is CORRECT? A) All genomes are encoded in DNA only. B) All genomes are encoded in nucleic acids. C) All genomes are encoded in proteins only. D) The genetic instructions are decoded completely differently in each organism. E) Molecular studies suggest life evolved from multiple primordial ancestors.

Which of the following statements is TRUE? A) Eubacteria are prokaryotes while the archaea are eukaryotes. B) Archaea are more closely related to eukaryotes than to eubacteria. C) Eukaryotes are more closely related to eubacteria than to archaea. D) Viruses are more closely related to prokaryotes than to eukaryotes. E) Eubacteria, archaea, and eukaryotes are all equally related.

Which of the following types of cancer is associated with a defect in nucleotide-excision repair? A) retinoblastoma B) xeroderma pigmentosum C) cervical cancer D) chronic myelogenous leukemia E) Bloom syndrome

Which of the following would serve the LEAST well as a model for understanding basic mechanisms of inheritance? A) fruit flies B) humans C) yeast D) mice E) zebrafish

Which one of the following topics belongs to a different subdiscipline of genetics when compared with the rest? A) mechanism of gene regulation B) allele frequencies of a certain gene in different environments C) transcription D) chemical alternation of chromosomes E) mechanism of DNA replication

Why was the pea plant an ideal plant for Mendel to use? A) generation time that is several years B) simple traits that are easy to identify C) low numbers of offspring produced D) expensive and time-consuming to grow E) All of the answers are correct.

With the XX-XO sex determination system, generally: A) female offspring have one X chromosome, and it is inherited from their father. B) male offspring have one X chromosome, and it is inherited from their mother. C) male offspring have one X chromosome, and it is inherited from their father. D) female offspring have one X chromosome, and it is inherited from their mother. E) male offspring have two X chromosomes, one inherited from each parent.

_____ and _____ are chromosomal mutations that may activate cellular oncogenes by moving them to new regulatory sequences where they become overexpressed. A) Duplications; deletions B) Inversions; translocations C) Duplications; inversions D) Deletions; translocations E) Aneuploidy; deletions

Alfred Roca and his colleagues used DNA sequencing to reassess the genetic relationships among African elephants. What did they conclude? A) Genetic variation was uncommon in African elephants. B) Cladogenesis occurred within African elephants. C) There was extensive gene flow between forest and savannah elephants. D) The genetic variation correlates with differences in phenotype that had been previously observed. E) There was extensive difference in the mitochondrial genome between savannah and forest elephants.

B) Cladogenesis occurred within African elephants.

_____ is the movement of genes between populations. A) Evolution B) Migration C) Positive assortative mating D) Outcrossing E) Genetic drift

B) Migration

Considering the strengths and weaknesses of molecular data, what could one NOT argue to be true? A) Molecular methods can be used in all organisms since they all have proteins and DNA. B) Molecular data are not easily quantifiable, making analysis somewhat subjective. C) Molecular methods can access a large amount of data. D) Molecular data can provide direct information on the process of evolution. E) Molecular variation is clear and interpretable, even if the relationship between some traits and their underlying genes is complex.

B) Molecular data are not easily quantifiable, making analysis somewhat subjective.

When considering the gene pool of a population, Hardy-Weinberg equilibrium may apply to: A) only the entire genome but not individual loci. B) one locus but not necessarily another. C) dominant and recessive alleles but not codominant alleles. D) only to the effective number of breeders. E) only autosomal but not X-linked loci.

B) one locus but not necessarily another.

Before the advent of molecular techniques, researchers indirectly assessed genetic variation in populations through the study of _____ diversity. A) protein B) phenotypic C) mutational D) behavioral E) fossil

B) phenotypic

In most cases, different species are distinguished on the basis of: A) genetic differences. B) phenotypic differences. C) time since anagenesis. D) the absence of reproductive isolating mechanisms. E) differences in ploidy level.

B) phenotypic differences.

Can different species have very few visible morphological differences or none at all? A) no, because different species must have distinct, visible morphological differences B) yes, if they are not under selection to evolve such differences (cryptic species) C) yes, if they are hybrids of other species D) yes, when their DNA is identical E) no, because their DNA is not identical, and phenotype must always reflect genotype

B) yes, if they are not under selection to evolve such differences (cryptic species)

Which statement(s) about probabilities is/are TRUE? (Select all that apply.) A) The probability of a woman giving birth to three girls in a row is 1/2+1/2+1/2. B) The chi-square test is used to determine if observed outcomes are consistent with expected outcomes. C) The probability of two or more independent events occurring together is calculated by adding their independent probabilities. D) Branched diagrams are used for determining probabilities of various phenotypes or genotypes for genetic crosses involving more than one gene pair. E) The probability of rolling an even number on a single roll of a six-sided die is 1/6+1/6+1/ 6.

B,D,E

Which of the following characteristics of vaccines are required in order for them to be effective in immunization? (Select all that apply.) A. They must contain the entire pathogen. B. They must present antigenic surfaces recognized by immunoglobulin molecules. C. They must stimulate lymphocyte activity. D. They must stimulate the production of large quantities of plasma cells. E. They must stimulate the production of memory cells.

B. They must present antigenic surfaces recognized by immunoglobulin molecules. C. They must stimulate lymphocyte activity. E. They must stimulate the production of memory cells.

Unlike most examples of this trait, the height characteristic that Mendel studied in pea plants exhibited _____ variation. A.continuous B.discontinuous C.meristic D.threshold E.quantitative

B. discontinuous

Suppose a new species of shark is discovered, and the dorsal fin length is found to be determined by additive alleles at three independently assorting loci (A and a, B and b, C and c). The dorsal fin length of aabbcc sharks is 12 cm and the dorsal fin length of AABBCC sharks is 30 cm. Assuming that the alleles contribute equally, which of the following genotypes would represent a shark with a dorsal fin length of 18 cm? A.aaBbcc B.AAbbcc C.AaBbCc D.AABBcc E.AaBbcc

B.AAbbcc

A gene does not contain the necessary restriction enzyme sites for cloning into a plasmid vector. What is a possible option? A.Increase the amount of gene used. B.Add linkers to generate new restriction enzyme sites. C.Use a cosmid as a cloning vector. D.Use dideoxy sequencing to obtain the sequence of the gene. E.Cut the DNA with a blunt end cutter.

B.Add linkers to generate new restriction enzyme sites.

Which of the following is TRUE of noncoding DNA? A.It is not essential for life in most organisms. B.It can contain sequences to which proteins can bind and influence gene expression. C.It can contain genes that code for rRNA and tRNA. D.It contains a high percentage of introns. E.These regions have a low gene density.

B.It can contain sequences to which proteins can bind and influence gene expression.

Which of the following statements is TRUE of genetic maps? A.They are derived from direct analysis of DNA. B.They are based on frequencies of recombination between loci. C.They have a high level of detail rivaling that of physical maps. D.They always accurately correspond to physical distances between genes. E.They are more accurate than physical maps.

B.They are based on frequencies of recombination between loci.

Which of the following is NOT a potential benefit of using transgenic plants? A.They can reduce the use of harmful chemical pesticides in the United States and thus provide an ecological benefit. B.They can generate restriction enzyme sites on a foreign gene of interest to be cloned. C.They often increase yields, providing more food per acre and reducing the amount of land needed for agricultural use. D.They can allow crops to be grown on land previously unavailable for productive agricultural use. E.They can be used to express large quantities of specific biological products more cheaply and quickly than by expression in animal systems.

B.They can generate restriction enzyme sites on a foreign gene of interest to be cloned.

Which of the following statements is NOT true regarding the basic components required for a bacterial cloning vector? A.Selectable markers provide a means for preferentially allowing growth of only those bacterial cells that have been transformed with the cloning vector. B.Unique restriction enzyme sites allow for larger pieces of foreign DNA to be inserted into the bacterial cloning vector. C.Unique restriction enzyme sites provide a means for inserting the foreign DNA into the cloning vector at a specific known sequence site. D.A bacterial origin of replication ensures that the plasmid is replicated while present within the bacterial cell. E.Selectable markers provide a means for selecting cells that have been transformed with a recombinant plasmid.

B.Unique restriction enzyme sites allow for larger pieces of foreign DNA to be inserted into the bacterial cloning vector.

Do the principles discovered by Mendel for discontinuous traits also apply to the inheritance of traits that exhibit continuous variation? Why or why not? A.Yes. The environmental factors that control continuous traits also control discontinuous traits according to Mendel's principles. B.Yes. Quantitative characteristics can be explained by additive effects of multiple genes, but the behavior of each gene can be determined by Mendel's principles. C.No. Continuous traits are controlled by both genes and the environment and, therefore, Mendel's principles would not apply. D.No. Discontinuous traits are the result of multiple genes that have additive effects and the behavior of continuous traits as defined by Mendel is the result of just a few loci. E.No. Mendel's principles of inheritance cannot be applied to quantitative traits because they do not involve dominance relationships.

B.Yes. Quantitative characteristics can be explained by additive effects of multiple genes, but the behavior of each gene can be determined by Mendel's principles.

A section of a genome is cut with three enzymes: A, B, and C. Cutting with A and B yields a 10-kb fragment. Cutting with B and C yields a 2-kb fragment. What is the expected result from a digest with A and C, if the C site lies in between the A and B sites? A.a 12-kb fragment B.an 8-kb fragment C.an 8-kb and a 2-kb fragment D.a 10-kb and a 2-kb fragment E.a 10-kb, an 8-kb, and a 2-kb fragment

B.an 8-kb fragment

Since the entire population is too large to work with, a sample is often used to characterize the population. This sample should: A.be at most 5% of the population size to minimize the computational efforts. B.be randomly selected so that it represents the entire population. C.include individuals that are selected to fully represent the extreme values in the distribution. D.be small enough to mitigate against chance events skewing the distribution of the sample.

B.be randomly selected so that it represents the entire population.

Linkage disequilibrium is the nonrandom association among SNPs within a haplotype. Over time, would you expect linkage disequilibrium among markers to be maintained, to increase, or to decrease? A.decrease, because random mutation will generate new SNPs that will give rise to new haplotypes B.decrease, because crossing over will break up the physical linkage among markers C.increase, because unequal crossing over between SNPs will decrease the physical distance between them D.increase, because positive selection will cause the haplotype to become more common E.be maintained, because there is no selective pressure to change the frequency of haplotypes in the population

B.decrease, because crossing over will break up the physical linkage among markers

A student carries out PCR using the following steps:Step 1: 94°C for 1 minuteStep 2: 60°C for 30 secondsStep 3: 72°C for 30 seconds Which of the following lists the CORRECT terms for these three steps? A.denaturation of the double-stranded template, extension of the new DNA molecules, primer annealing B.denaturation of the double-stranded template, primer annealing, extension of the new DNA molecules C.denaturation of the double-stranded template, extension of the new DNA molecules, hybridization of the template D.degradation of the template, primer annealing, extension of the new DNA molecules E.hybridization of the single-stranded templates, primer annealing, extension of the new DNA molecules

B.denaturation of the double-stranded template, primer annealing, extension of the new DNA molecules

Phenotypic variation in a trait is often represented as a _____, which graphs the number of each phenotypic class in a sample. A.bimodal distribution B.frequency distribution C.regression line D.correlation E.variance plot

B.frequency distribution

A QTL: A.is one of the genes that influences a trait B.is a chromosomal region containing genes that influence a quantitative trait C.will not contain any genes other than the ones influencing a trait D.is a measure of the phenotypic variation in a quantitative trait E.is a measure of the genetic variation in a quantitative trait

B.is a chromosomal region containing genes that influence a quantitative trait

Two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) is a technique wherein proteins are separated in one dimension by a chemical property and in a second dimension by a different property. By what property are proteins separated in the second dimension? A.electrical charge B.molecular mass C.posttranslational modification D.isotope E.hydrophobic index

B.molecular mass

Quantitative characters often exhibit a _____ distribution. A.skewed B.normal C.bimodal D.covariance E.tangential

B.normal

If a restriction enzyme cuts a circular DNA into three fragments, how many restriction sites are there in the DNA? A.two B.three C.four D.six E.five

B.three

The three point test cross. A fish breeder has been trying to produce a more decorative fish to sell to customers. She has identified three dominant traits glows in the dark (G), bright blue color body (B), colorful head (C) that are more desirable than the wild type traits of non-glowing (h), grey colored body (b), black head (c). From her original crosses she determines that the three genes are linked. To map the genes, she performs a test cross and obtains the following results. Based on these data, what is the correct gene order? PHENOTYPES NUMBERS of PROGENY OBSERVED (g b c) - 366 (g b C) - 122 (g B C ) - 6 (G b C) - 66 (g B c) - 69 (G B c) - 113 (G B C) - 351 (G b c ) - 4

BGC

Determine the correct order of the genes on the chromosome, given the following information: Genes O and B cross over at a rate of 15% Genes O and I cross over at a rate of 5% Genes I and B cross over at a rate of 20%

BOI

Cloning is a procedure by which exact genetic duplicates are made. A litter of cloned rabbits was born from a single surrogate mother rabbit. Despite being genetically identical, each of the baby rabbits looked very different from one another. Explain in detail why this might have occurred.

Because phenotypic variation is made up of both genetic variation and environmental variation, and we are told that the rabbits are genetically identical, there must be environmental variation that explains the phenotypic differences. Even within the seemingly "constant" environment of a rabbit's womb, there is environmental variation.

Suppose that an apparently female athlete fails a gender test and is not allowed to compete in her event. The gender test is based on examination of cheek cells for the presence of one or more Barr bodies. Later, it is discovered that the athlete has androgen-insensitivity syndrome. Explain why the athlete failed the gender test. What did the technician see in the test and how was it interpreted?

Because the athlete is XY, the technician would have seen no Barr bodies in her cells. The absence of Barr bodies is normally characteristic of males, so the test was interpreted to indicate that the athlete is genetically male.

The experiments of Gregor Mendel can be placed into which subdivision of genetics? A) molecular genetics B) population genetics C) transmission genetics D) molecular genetics and transmission genetics E) population genetics and transmission genetics

A woman has normal vision although her maternal grandfather (her mother's father) had red- green color blindness, a sex-linked recessive trait. Her maternal grandmother and the woman's own father are assumed to not possess a copy of the mutant allele. The woman marries a man with normal vision although his father was color blind. What is the probability that the first child of this couple will be color blind? A) 1/2 B) 1/4 C) 1/8 D) 1/16 E) 1/12

Activin is a protein that normally exists in a gradient within certain tissues in developing embryos. Certain undifferentiated cells cultured without activin produce epidermal cells. However, activin induces these same cells to adopt other fates (e.g., blood, muscle, heart), depending on the concentration of activin. Based on these observations, activin acts as a(n): A) transcription factor. B) cell-surface receptor. C) morphogen. D) second messenger. E) activator.

Albinism is rare in most human populations, occurring at a frequency of about 1 in 20,000 people. However, the trait occurs at a frequency of 1 in 200 in certain Hopi villages of Black Mesa in Arizona. In light of this example and others that you might be aware of, what can you conclude about particular alleles such as the allele for albinism? A) An allele that leads to an abnormal phenotype will be rare in most populations but common in Native American populations. B) An allele that leads to abnormal phenotype will not be beneficial in any population. C) An allele that leads to an abnormal phenotype may be beneficial in some environments but harmful in others. D) An allele that leads to an abnormal phenotype will rise in frequency after many generations. E) An allele that leads to an abnormal phenotype will soon disappear from a population

Certain viruses are instrumental in converting proto-oncogenes to oncogenes. This conversion most commonly results because: A) viruses specifically infect cells that contain proto-oncogenes. B) only viruses contain genes that can convert proto-oncogenes into oncogenes. C) the proto-oncogenes are more likely to undergo mutation or recombination within a virus. D) viruses contain the remainder part of the DNA that is added to the proto-oncogene to form the oncogene.

In a certain cell line, a tumor-suppressor gene is translocated to a different location under the control of a strong promoter. Which of the following would be TRUE of this cell line compared to a cell line without this translocation? A) The cells will have an increase in angiogenesis. B) The cells will be at an increased risk of transitioning from benign to malignant. C) The cells will show a lower amount of proliferation. D) The cells will be at a slightly increased risk of cancer. E) It depends where the gene was translocated.

In a typical flowering plant, a pollen grain that lands on a stigma grows a pollen tube to deliver _____ (how many?) sperm to the ovary. Fusion of a sperm with an egg produces a _____ n cell called a _____. A) 1; 1; zygote B) 2; 1; megasporocyte C) 2; 2; zygote D) 1; 2; microsporocyte E) 1; 2; megasporocyte

Many viruses that are associated with cancers in animals are _____ that use reverse transcriptase. A) papilloma viruses B) Epstein-Barr viruses C) retroviruses D) hepatitis B viruses E) None of the answers is correct.

Most cancers are assumed to arise through which of the following? A) errors in transcription B) the production of unbalanced gametes because of nondisjunction during meiosis C) genetic or epigenetic changes in somatic cells D) delayed cell division during early embryogenesis E) No correct answer is provided.

The complete genetic makeup of any organism is referred to as a: A) phylogeny. B) pheynotype. C) genome. D) genotype. E) single-nucleotide polymorphism.

The normal activity of the retinoblastoma (Rb) protein in the cell is to: A) inhibit p53 activity. B) suppress transcription of tumor-suppressor genes. C) regulate the progression of from G1 to S in the cell cycle. D) induce cyclin-CDK complex formation. E) block the initiation of anaphase during the cell cycle.

To provide food for the developing embryo, a tissue called endosperm is produced through double fertilization. Endosperm has a ploidy of: A) 1n. B) 2n. C) 3n. D) 4n. E) 5n.

What specifically do most people inherit when they inherit a predisposition to a particular cancer such as retinoblastoma? A) a mutation that causes the overexpression of a DNA repair gene B) a mutation that causes telomerase to have reduced expression in somatic cells C) a deleterious mutation in one copy of a tumor-suppressor gene D) a deletion that removes one copy of an oncogene E) an extra X chromosome from the mother

Which of the following are NOT prokaryotes? A) eubacteria B) archaea C) viruses D) ancient bacteria

Which of the following species is considered a model genetic organism? A) the plant Linaria vulgaris B) the deer mouse Peromyscus maniculatus C) the worm Caenorhabditis elegans D) the frog Hyla chrysoscelis E) the chimpanzee Pan troglodytes

Which of the following statements about homeotic genes is INCORRECT? A) Homeotic genes were first identified in invertebrates, but their homologs were found in almost all organisms. B) All homeotic genes contain consensus sequences that result in a specific DNA-binding motif. C) In vertebrates, homeotic genes are organized into two distinct clusters. D) All homeotic genes encode transcription factors that direct further gene expression. E) Homeotic genes exhibit a relationship between their order on the chromosome and the timing of their expression.

Which of the following statements is FALSE? A) Generally, chromosomes of prokaryotes are circular. B) Prokaryotes usually have a single molecule of DNA. C) Generally, chromosomes of eukaryotes are circular. D) Eukaryotes usually have multiple chromosomes. E) Eukaryote chromosomes are usually linear.

You are studying body color in an African spider and have found that it is controlled by a single gene with four alleles: B (brown), br (red), bg (green), and by (yellow). B is dominant to all the other alleles, and by is recessive to all the other alleles. The bg allele is dominant to by but recessive to br . You cross a pure-breeding brown spider with a pure-breeding green spider. Predict the phenotype of the progeny. A) half brown, half green B) three-fourths brown, one-fourth green C) all brown D) all green E) all yellow

If there are two alleles, A and a, in a population and the population is at Hardy-Weinberg equilibrium, which frequency of A would produce the greatest frequency of heterozygotes? A) 0.1 B) 0.25 C) 0.5 D) 0.75 E) 1

C) 0.5

When a population is in Hardy-Weinberg equilibrium, what is the significance of two alleles with equal frequencies (p = q = 0.5)? A) These are the allelic frequencies found in most populations. B) These allelic frequencies maximize the proportion of homozygotes in the population. C) These allelic frequencies maximize the proportion of heterozygotes in the population. D) These allelic frequencies guarantee that neither allele will become fixed in a population. E) These allelic frequencies minimize the proportion of heterozygotes in the population.

C) These allelic frequencies maximize the proportion of heterozygotes in the population.

The observation that some genes are mosaics of other genes can be explained by: A) evolution. B) horizontal gene transfer. C) exon shuffling. D) gene duplication. E) pseudogenes.

C) exon shuffling.

Which reproductive isolating mechanism is exhibited by two different species of tree frogs when their males vocalize their distinct mating songs at the same time in the same forest? A) prezygotic ecological B) postzygotic C) prezygotic behavioral D) prezygotic temporal E) prezygotic mechanical

C) prezygotic behavioral

Which region of a gene should have the HIGHEST rates of substitution? A) first position of a codon B) second position of a codon C) third position of a codon D) 5ʹ flanking region E) 3ʹ untranslated region

C) third position of a codon

Huntington's disease tends to strike earlier and lead to a more rapid progression of symptoms as it moves from generation to generation. Also, it tends to strike earlier and progress more rapidly when it is passed from the father to his children rather than from the mother. Which genetic phenomenon (or phenomena) is/are likely operating here? (Select all that apply.) A) incomplete penetrance B) sex-limited inheritance C) genetic anticipation D) parental imprinting E) epistasis

C,D

In the introduction to this chapter, the use of the CRISPR-Cas9 system to make a deletion of exon 23 containing a premature stop codon in mdx mice was described. The resulting mice had partially restored dystrophin protein and muscle function. Which of the following CRISRP-Cas9 mediated changes might lead to a better restoration of dystrophin protein and muscle function? A. A deletion of exon 24 in addition to exon 23 B. A deletion of intron 23 C. A deletion of 30 bases within exon 23 D. A deletion of 25 bases within exon 21 E. An insertion of a corrected copy of exon 23 after the mutant exon 23

C. A deletion of 30 bases within exon 23

A scientist attempts to use the CRISPR-Cas9 system to edit a single gene within a cell. She finds that, in addition to editing the desired gene, she has edited several other genes as well. What are reasonable options for her to try next in order to target just the gene of interest? (Select all that apply.) A. Add less Cas9 enzyme. B. Create a longer sgRNA. C. Try a different sgRNA that will still pair within the gene of interest. D. Use separate crRNA and tracrRNA molecules. E. Use a higher-fidelity version of Cas9.

C. Try a different sgRNA that will still pair within the gene of interest. E. Use a higher-fidelity version of Cas9.

During gel electrophoresis, large DNA fragments will _____ small DNA fragments. A.migrate more rapidly than B.migrate at the same speed as C.migrate more slowly than D.cause degradation of E.separate into

C. migrate more slowly than

Which of the following represents an appropriate cloning vector for cloning a gene into a bacterial cell? A.YAC B.Ti plasmid C.plasmid D.Agrobacterium tumefaciens E.lacZ

C. plasmid

_____ is a way to measure the strength of the association between two variables. A.Regression B.Covariance C.Correlation D.Variance E.Standard deviation

C.Correlation

What is the purpose of Taq polymerase in a PCR reaction? A.DNA denaturation B.primer annealing C.DNA synthesis D.heating of the reaction E.heating of the reaction and DNA denaturation

C.DNA synthesis

Which of the following statements does NOT describe a challenge of working at the molecular level? A.Cells contain thousands of genes. B.Individual genes cannot be seen. C.It is not possible to isolate DNA in a stable form. D.A genome can consist of billions of base pairs. E.No physical features mark the beginning or end of a gene.

C.It is not possible to isolate DNA in a stable form.

Which of the following statements is NOT correct regarding type II restriction enzymes? A.They can create blunt ends. B.They make double-stranded cuts in DNA. C.They recognize specific sequences and make cuts further away from the recognition sequence. D.They are named based on their bacterial origin.

C.They recognize specific sequences and make cuts further away from the recognition sequence.

All of the following are requirements of a bacterial cloning vector EXCEPT: A.origin of replication. B.unique restriction enzyme sites. C.Ti plasmid. D.selectable markers.

C.Ti plasmid.

_____ is measured in terms of the original units squared. A.Mean B.Standard deviation C.Variance D.Correlation coefficient E.Narrow-sense heritability

C.Variance

Which of the following is NOT a bacterial cloning vector? A.plasmid B.bacteriophage λ C.agrobacterium D.bacterial artificial chromosome E.cosmid

C.agrobacterium

For a genetic map of a chromosome, distances are measured in units of: A.restriction sites. B.RFLPs. C.centiMorgans. D.base pairs. E.contigs.

C.centiMorgans.

Ampicillin resistance is to ampR as _____ is to lacZ. A.Bt toxin B.G418 C.cleavage of X-gal D.penicillin resistance E.gancyclovir

C.cleavage of X-gal

Phenotypic correlation may be due to genetic correlations such as _____, which is when one gene influences two or more traits. A.broad-sense heritability B.dominance genetic variance C.pleiotropy D.QTL E.thresholds

C.pleiotropy

Describe the epigenetic changes that occur in cells during development and the role they play in differentiation of cell types within a multicellular organism.

Cell differentiation is driven by regulation of gene expression. Genes whose products are needed for the structure and function of a particular cell are turned on, and those whose products are not needed are turned off. Epigenetic changes are heritable alterations to DNA and chromatin structure that can affect gene expression. Because these changes are heritable during cell division, gene expression states (on or off) established within a cell early in development can be passed on to daughter cells and other descendant cells. Epigenetic changes can include DNA methylation, modification of histone proteins, and chromatin remodeling. In early stages of development, genes that may be required later in development are often held in a transiently silent state by histone modifications. These modifications are generally flexible and easily reversed, allowing for later activation. Genes can be more permanently silenced by DNA methylation.

During prophase I of meiosis, crossing over is indicated by what microscopically visible structure?

Chiasmata (chiasma) or the synaptonemal complex

What have the cloning experiments in plants and animals confirmed with regard to developmental processes?

Cloning experiments have demonstrated that genetic material is not lost or permanently altered during development, and that development must involve selective, coordinated expression of genes.

A female with androgen-insensitivity syndrome, a sex-linked recessive condition, has: A) two X chromosomes, both carrying mutant alleles in the gene that makes the androgen receptor. B) a pair of ovaries that overproduce estrogen. C) an XXX chromosome constitution that causes her not to produce testosterone. D) a pair of testes that produce testosterone. E) an inactive SRY gene.

A mother of blood type A gives birth to a child with blood type O. Which of the following could NOT be the blood type of the father? A) A B) B C) O D) AB E) Any of these is a possible blood type of the father.

A phenotypically normal man has phenotypically normal parents but he has a sister who has cystic fibrosis caused by a recessive mutant allele. What is the probability that the man is heterozygous for the cystic fibrosis allele? A) 1/4 B) 1/2 C) 3/4 D) 2/3 E) 1/3

Achondroplasia is a common cause of dwarfism in humans. All individuals with achondroplasia are thought to be heterozygous at the locus that controls this trait. When two individuals with achondroplasia mate, the offspring occur in a ratio of 2 achondroplasia : 1 normal. What is the MOST likely explanation for these observations? A) Achondroplasia is incompletely dominant to the normal condition. B) Achondroplasia is codominant to the normal condition. C) The allele that causes achondroplasia is a dominant lethal allele. D) The allele that causes achondroplasia is a recessive lethal allele. E) The allele that causes achondroplasia is a late-onset lethal allele.

Assume that a geneticist is doing a study with a wild mouse species. She captures 100 of these mice, takes a DNA sample from each, and sequences the same specific gene from each mouse. This gene has two alleles within this population. She then calculates the frequency of each of the two alleles from the sequencing results. Which subdivisions of genetics would this study include? A) transmission and population genetics B) transmission and molecular genetics C) molecular genetics only D) molecular and population genetics E) transmission genetics only

The p53 gene is important in controlling apoptosis, but it also plays a role i: A) initiating mitosis. B) controlling cell adhesion. C) opening ion channels. D) duplicating the centrosome. E) preventing aneuploidy by regulating the spindle-assembly checkpoint.

The study of the expression, localization, and interactions of the complete set of proteins found in a given cell is called: A.genomics. B.bioinformatics. C.metagenomics. D.proteomics. E.transcriptomics.

D.proteomics.

Consider the Ras signal-transduction pathway. Suppose a mutation occurred in the gene that encodes MEK that renders it nonfunctional. Which of the following effects would you see in this situation? A) Binding of the growth factor to the receptor would occur, but the receptor's conformational change that is needed for the pathway to go forward would not occur. B) Activated Ras would no longer have the ability to activate Raf, and the signaltransduction pathway would be halted at this step. C) Ras would lose the ability to bind GTP and thus could no longer become activated, and the signal-transduction pathway would be halted at this step. D) MAP kinase would not be activated and thus could not move into the nucleus to activate transcription factors. E) Inactive Ras would move into the nucleus and inactivate tumor-suppressor transcription factors, which could ultimately result in cancer.

Identify a FALSE statement from the following descriptions of genetics. A) Humans first applied genetics to the domestication of plants and animals between approximately 10,000 and 12,000 years ago. B) Some viruses use RNA to carry their genetic information. C) Albinism results from a mutation in the genes that control the synthesis and storage of melanin. D) All human traits that display blending inheritance are affected by a single gene. E) The process by which genetic information is copied and decoded is similar for all forms of life.

Identify a TRUE statement from the following descriptions concerning genetics. A) The theory of pangenesis states that all living organisms are composed of cells. B) Bacteria and viruses are not useful in studying genes and inheritance because they are structurally and metabolically different from eukaryotic cells. C) Charles Darwin accurately described the laws of inheritance in his landmark book, On the Origin of Species. D) Many human traits, such as skin and hair color, are determined by more than a single gene. E) Evolution can occur without genetic changes in the population.

In a cross between pure-breeding tall plants with pure-breeding short plants performed by Mendel, all of the F1 are tall. When these plants are allowed to fertilize themselves, the F2 plants occur in a ratio of 3 tall to 1 short. Which of the following is NOT a valid conclusion from these results? A) The allele that produces the tall condition is dominant to the allele that produces the short condition. B) The difference between tall and short stature in these lines is controlled by a single gene pair. C) During production of gametes in F1 plants, the tall and short alleles segregate from each other equally into the gametes. D) The tall and short traits assort independently of each other in this cross. E) Fertilization occurs randomly between gametes carrying the tall and short alleles

In humans, occasionally a baby is found that has the XX chromosomal karyotype but is phenotypically male. Which of the following statements might be a CORRECT explanation for at least some of these unusual cases? A) A mutation has occurred in the SRY gene making it inactive. B) An extra pierce of autosomal chromosome 15 is probably present in the genome but is too small to be detected. C) A small piece of autosomal chromosome 15 is missing but is too small to be detected. D) A piece of chromosomal material containing an active SRY gene is found attached to one of the X chromosomes. E) The ratio of number of X chromosomes to number of sets of chromosomes is incorrect.

Mutations in proto-oncogenes are generally _____ whereas mutations in tumor-suppressor alleles are generally _____. A) deletions; duplications B) recessive; dominant C) duplications; deletions D) dominant; recessive E) deletions; base-pair substitutions

Prokaryotic chromosomes do NOT have telomeres because they: A) do not go through mitosis. B) do not go through DNA replication. C) are in the cytoplasm. D) are circular. E) have no centromeres.

Suppose that a diploid cell contains 8 chromosomes (2n = 8). How many different combinations in the gametes are possible? A) 2 B) 4 C) 8 D) 16 E) 64

The cells of a mature pea plant have 14 chromosomes. How many chromosomes does a nucleus in the pea endosperm contain? A) 31/2 B) 7 C) 14 D) 21 E) 30

The complete genetic makeup of an organism is referred to as its: A)chromosome. B)alleles. C)locus. D)genome. E)phenotype.

The highly organized internal scaffolding of the nucleus is called the: A) histone complex. B) spindle microtubules. C) nuclear cohesion. D) nuclear matrix. E) nuclear envelope.

Which of the following chromosome constitutions would never lead to a viable human baby being born? A) XXX B) XYY C) XO (O = the absence of a second chromosome) D) YY E) XXY

Which of the following statements accurately describes antibodies? A) Kappa and lambda are the two types of immunoglobulin heavy chains. B) Genes coding for antibody constant regions undergo somatic recombination to generate diversity. C) Antigens are always proteins that are exposed on the surface of foreign invaders. D) Antigen-binding sites are located at the tips of the two arms of the Y-shaped antibody. E) The variable region segments (V genes) are only subjected to somatic recombination to contribute to different antigen recognition as they come in direct contact with antigens.

Which of the following statements is TRUE? A) The genotype is the physical appearance of a trait. B) Alleles, genes, and loci are different names for the same thing. C) The phenotype of a dominant allele is never seen in the F1 progeny of a monohybrid cross. D) A testcross can be used to determine whether an individual is homozygous or heterozygous for a dominant allele.

Suppose that in a population the frequency of a particular recessive condition is 1/400. Assume the presence of only a dominant allele (A) and a recessive allele (a) in the population and that the population is at Hardy-Weinberg equilibrium. What is the frequency of the recessive allele that causes the condition? A) 0.000625 B) 0.0025 C) 0.025 D) 0.05 E) 0.95

D) 0.05

If there is random mating in a population and no evolutionary forces are acting on the population, what will be the expected outcome? A) The allelic frequencies will remain the same, but the genotypic distribution will change. B) The genotypic distribution will remain the same, but the allelic frequencies will change. C) Both the genotypic distribution and the allelic frequencies will change. D) Both the genotypic distribution and the allelic frequencies will remain the same. E) No prediction can be made about the genotypic distribution and allelic frequencies from one generation to the next.

D) Both the genotypic distribution and the allelic frequencies will remain the same.

_____ is the splitting of one lineage into two distinct lineages. A) Genesis B) Anagenesis C) Phylogenesis D) Cladogenesis E) Neogenesis

D) Cladogenesis

_____ ultimately produces all new genetic variation in a population. A) Outcrossing B) Migration C) Evolution D) Mutation E) Equilibrium

D) Mutation

Which of the following markers is NOT used to investigate genetic variation in natural populations? A) DNA sequence B) RFLP C) microsatellite D) isotope E) allozyme

D) isotope

A new kind of tulip is produced that develops only purple or pink flowers. Assume that flower color is controlled by a single-gene locus and that the purple allele ( C ) is dominant to the pink allele ( c ). A random sample of 1000 tulips from a large cultivated field yields 847 purple flowers and 153 pink flowers. What is the frequency of the purple and pink alleles in this field population? A) purple allele frequency = 0.847, pink allele frequency = 0.153 B) purple allele frequency = 0.153, pink allele frequency = 0.847 C) purple allele frequency = 0.82, pink allele frequency = 0.18 D) purple allele frequency = 0.61, pink allele frequency = 0.39 E) purple allele frequency = 0.39, pink allele frequency = 0.61

D) purple allele frequency = 0.61, pink allele frequency = 0.39

_____ can cause a single genotype to produce a range of potential phenotypes. A.Epistasis B.Genetic variance C.Threshold effects D.Environmental effects E.Heritability

D. Environmental effects

Which of the following genes determines the identity of individual segments during development? A.bicoid B.nanos C.cactus D.disheveled E.dorsal

D. disheveled

In a population of pigs, the average body weight is 178 kg. Suppose you select the 15 largest pigs, whose average body weight is 205 kg, and interbreed them. The average body weight of the offspring of the selected pigs is 191 kg. If you were to select pigs that have an average weight of 240 kg, what would be the predicted weight of the progeny produced by the selected pigs? A.30 B.62 C.115 D.208 E.270

D. 208

A scientist edits a mammalian genome by inserting a GFP reporter sequence downstream of a gene of interest. Which of the following methods is she likely to have used to make this change? A.site-directed mutagenesis B.oligonucleotide-directed mutagenesis C.CRISPR-Cas9 genome editing followed by nonhomologous end joining (NHEJ) D.CRISPR-Cas9 genome editing followed by homologous recombination (HR) with a donor template E.mutagenesis with radiation

D. CRISPR-Cas9 genome editing followed by homologous recombination (HR) with a donor template

A student carries out PCR using the following steps:Step 1: 94°C for 1 minuteStep 2: 60°C for 30 secondsStep 3: 72°C for 30 seconds After subjecting his PCR reaction to gel electrophoresis, the student sees no PCR product on the gel. What error(s) might he have made? (Select all that apply.) A. He carried out step 1 at too low a temperature. B. He carried out step 1 at too high a temperature. C. He carried out step 2 at too low a temperature. D. He carried out step 2 at too high a temperature. E. He carried out step 3 for too short a time.

D. He carried out step 2 at too high a temperature. E. He carried out step 3 for too short a time.

The _____ is the statistic that measures the spread of a distribution around the mean. A.covariance B.correlation coefficient C.regression coefficient D.variance E.average

D. variance

Flower diameter in sunflowers is a quantitative trait. A plant with 6-cm flowers, from a highly inbred strain, is crossed to a plant with 30-cm flowers, also from a highly inbred strain. The F1 have 18-cm flowers. F1 × F1 crosses yield F2 plants with flowers ranging from 6 to 30 cm in diameter, in approximately 4-cm intervals (6, 10, 14, 18, 22, 26, 30). An 18-cm F1 plant is crossed to a 6-cm plant. What is the probability of an offspring with one additive allele, if all genes that influence this trait are unlinked? A.1/3 B.1/4 C.1/6 D.3/8 E.1/16

D.3/8

Which of the following would be MOST appropriate for cloning a gene that is 300 kb in size? A.plasmid B.cosmid C.phage lambda D.BAC E.yeast phage E.yeast phage

D.BAC

Consider a tobacco plant cell that was able to express a toxin that was lethal to insects and was resistant to the antibiotic kanamycin. Which of the following genes would this cell contain? A.Bt B.neo+ C.lacZ D.Bt and neo+ only E.Bt, neo+, and lacZ

D.Bt and neo+ only

A scientist is studying a normal tissue sample and a cancerous tissue sample. What method might she use to determine whether the transcription of gene X is upregulated in the cancerous tissue sample? A.Carrying out a Southern blot using the cancerous tissue sample only B.Carrying out a Southern blot using both samples C.Carrying out a Northern blot using the cancerous tissue sample only D.Carrying out a Northern blot using both samples E.Carrying out a Western blot using the cancerous tissue sample only

D.Carrying out a Northern blot using both samples

Which of the following statements CORRECTLY describes DNA ligase? A.DNA ligase forms hydrogen bonds between nucleotide bases. B.DNA ligase can seal nicks between amino acids. C.DNA ligase recognizes and cuts at specific sequences. D.DNA ligase is necessary for creating recombinant plasmids. E.DNA ligase is a requirement of a sequencing reaction.

D.DNA ligase is necessary for creating recombinant plasmids

Which of the following is a disadvantage of map-based sequencing over shotgun sequencing? A.Map-based sequencing minimizes the amount of repeat sequencing in which the same region is sequenced several times. B.Map-based sequencing yields well-characterized physical maps as well as actual sequences. C.The relationship of overlapping fragments to sequences is known before sequencing begins. D.Map-based sequencing is more time-consuming because extensive mapping is required before sequencing starts. E.Restriction patterns can be used to identify overlapping clones.

D.Map-based sequencing is more time-consuming because extensive mapping is required before sequencing starts.

In the genetic map of the human genome, one map unit is approximately 850,000 bp. For the genome of the eukaryotic yeast Saccharomyces cerevisiae, one map unit is approximately 3000 bp. Why is a map unit so different in these two different types of organisms? A.A map unit is the amount of measured recombination between two linked points in a genome, and humans have more SNPs than Saccharomyces cerevisiae that can serve as genetic markers. B.An increased number of noncoding introns in humans suppresses recombination and leads to larger physical distances for each map unit. C.Saccharomyces cerevisiae has fewer predicted genes than humans, which means that less recombination is required in yeast cells. D.The amount of homologous recombination per DNA length must be lower in humans than in Saccharomyces cerevisiae. E.Humans have more chromosomes and, therefore, have more linkage groups than Saccharomyces cerevisiae.

D.The amount of homologous recombination per DNA length must be lower in humans than in Saccharomyces cerevisiae.

Two highly inbred tobacco plants are crossed. One has dark green leaves. The other has yellow leaves. The F1 have light green leaves. Five hundred progeny from F1 × F1 crosses are analyzed. Their leaves show continuous variation in color, but none has dark green or yellow leaves. What do these data suggest about the number of genes determining this trait? A.There are two genes that determine this trait. B.There are three genes that determine this trait. C.There are four genes that determine this trait. D.There are more than four genes that determine this trait. E.There is not enough information to estimate the number of genes.

D.There are more than four genes that determine this trait.

A series of experiments shows that oil content in a diploid grain is influenced by five genes (a through e) with additive alleles. The highest-producing strain has 20% oil content; the lowest has close to 0%. A plant of unknown genotype has an oil content of 12%. What is a possible genotype for this plant (+ = additive alleles)? A.a+a+b+b+c+c+d+de+e B.a+a+b+b+ ccddee C.a+a+b+bccddee D.aab+bc+cd+d+e+e+ E.a+a+b+b+c+c+d+dee

D.aab+bc+cd+d+e+e+

For a physical map of a chromosome, distances are measured in units of: A.map units. B.RFLPs. C.centiMorgans. D.base pairs. E.contigs.

D.base pairs.

A set of overlapping DNA fragments that form a contiguous stretch of DNA is called a: A.chromosome. B.sequence. C.map. D.contig. E.clone.

D.contig.

A population may eventually stop responding to artificial selection because: A.individuals in the population have become homozygous for the alleles responsible for the trait. B.natural selection opposes any further change in the characteristic. C.natural selection can no longer enhance the results of artificial selection. D.individuals in the population have become homozygous for the alleles responsible for the trait and natural selection opposes any further change in the characteristic. E.individuals in the population have become homozygous for the alleles responsible for the trait and natural selection can no longer enhance the results of artificial selection.

D.individuals in the population have become homozygous for the alleles responsible for the trait and natural selection opposes any further change in the characteristic.

Southern blotting is a technique used to transfer _________ to a nitrocellulose medium.

DNA

Explain how UV light induces mutations in E. coli's DNA both immediately and long-term.

DNA bases absorb UV light, resulting in the formation of covalent bonds between adjacent pyrimidines on the same strand of DNA. These pyrimidine dimers distort the DNA molecules and block replication by the most DNA polymerases. If the dimers are not repaired (e.g., by photolyase), the cell can replicate across the distorted region by using special replication machinery that is error-prone. Therefore, mutations result from error-prone replication in response to damage from UV light rather than directly from the damage itself.

Explain how UV light induces mutations in E. coli.

Which pairing of a protein and function is correct?

DNA polymerase 3- adding nucleotides to the 3' end of the growing strand of DNA AND Ligase- Joins adjacent DNA fragments

How is it possible that a DNA mutation would lead to an irregularly shaped protein being synthesized?

DNA mutations can change the primary structure of a protein because DNA codes for this amino acid sequence. This linear sequence of a.a. affects its ability to fold properly for example, the substitution of one amino acid for another in hemoglobin causes sickle-cell disease

What are two processes that determine how quickly mutations accumulate within a cell?

DNA repair and apoptosis are two processes that can affect how quickly mutations accumulate within a cell. Active DNA-repair processes usually limit the number of mutations that are created through mistakes in DNA replication and other sources. Often DNA repair is limited in cancer cells and mutations accumulate. When mutations accumulate and the cell becomes unable to maintain normal activities, it may undergo apoptosis and die. In many cancers the ability to undergo apoptosis is compromised and cells continue to grow and accumulate mutations.

A 24-year-old woman with myotonic dystrophy, a genetic disorder caused by a dominant mutant allele, has significant muscle weakness and wasting. She has a 1-year-old son with very poor muscle tone, severe weakness, and significant developmental delay. Her affected 55-year-old father has minor cataracts but no muscle weakness. Which of the following terms BEST describes this situation? A) codominance B) complementation C) multiple alleles D) compound heterozygote E) anticipation

A change in allele frequency within a population over time leads to: A) a genome. B) a phenotype. C) a genotype. D) mutations. E) evolution.

A man is heterozygous for a rare trait that is assumed to be caused by a dominant autosomal mutant allele. He marries a woman who is phenotypically normal. They have a phenotypically normal daughter who marries a phenotypically normal man. Unexpectedly their first child, a girl, has the same abnormal trait as her grandfather. Which of the following BEST explains this situation? A) The trait is really due a mutation in a cytoplasmic gene and can be only inherited from the mother. B) This is a sex-influenced trait and is expressed more often in females than in males. C) This is an example of genomic imprinting and the mutant allele is only expressed if it is inherited from the father. D) The mutant allele shows incomplete dominance when heterozygous with the normal allele. E) The mutant allele shows reduced penetrance and the normal daughter carries the mutant allele

A rare situation where only one of the two copies of a particular tumor-suppressor gene needs to be inactivated before there is a progression toward cancer is called: A) clonal evolution. B) loss of heterozygosity. C) signal transduction. D) aneuploidy. E) haploinsufficiency

If both husband and wife are known to be heterozygous for the autosomal recessive condition of albinism, what is the probability that among their four children, three will be normal and one will have albinism? A) 27/256 B) 3/4 C) 9/16 D) 13/32 E) 27/64

In the late 1990s what important discovery in genetics was made? A) The three-dimensional structure of DNA was described, which showed how DNA might be replicated. B) The first recombinant DNA experiments were performed that started the biotechnology field. C) DNA sequencing methods were first discovered. D) Genes were found to be located on chromosomes. E) Tiny RNAs were discovered that play important roles in the regulation of gene expression.

Regulation of apoptosis involves initial activation of the enzymes called _____, which act as proteases that can trigger a cascade of cellular protein degradation, bringing about eventual DNA fragmentation. A) apaptase B) acetylase C) demethylase D) nucleases E) caspases

Which of the following mechanism does NOT contribute to the diversity of antibody and T-cell receptors recognizing different antigens? A) junctional diversity B) somatic hypermutation C) somatic recombination D) pairing of different light and heavy chains E) pairing of different MHC loci

True or False: The genotype is the physical appearance of a trait.

False

Which of the following statements is FALSE? A) Tumors usually show a clonal evolution. B) Cervical cancer is associated with an animal virus. C) Some cancers are associated with reduced DNA repair. D) Epigenetic changes in somatic cells may be associated with some cancers. E) Most tumors arise from germ-line mutations that accumulate during our life span.

Which of the following statements is TRUE? A) Each subdiscipline of genetics is very specific as to what is explored and does not overlap with the other subdisciplines. B) All phenotypes or traits are always determined by multiple genes. C) Albinism arises from the overexpression of the gene that controls the synthesis and storage of melanin. D) Humans make excellent model organisms because they have a variety of well-defined traits. E) None of the statements provided are true.

Which one of the following pairings between the subdiscipline of genetics and the phenomenon is INCORRECT? A) evolution—population genetics B) gene regulation—molecular genetics C) allelic frequency alteration—population genetics D) arrangement of genes on chromosome—transmission genetics E)chemical nature of the gene—transmission genetics

_____ are sets of genes that are similar in sequence but encode different products. A) Codons B) Genomes C) Exons D) Pseudogenes E) Multigene families

E) Multigene families

The _____ is all of the genetic information within a Mendelian population. A) effective population size B) Hardy-Weinberg equilibrium C) fitness D) genotypic frequency E) gene pool

E) gene pool

The balance hypothesis does NOT suggest that: A) genetic variation in a population is mostly maintained by natural selection. B) overdominance is one type of natural selection favoring the maintenance of genetic variation. C) most molecular variants are not functionally equivalent. D) levels of genetic variation are increased by the role of natural selection. E) genetic drift and mutation are both important in determining levels of genetic variation within a population.

E) genetic drift and mutation are both important in determining levels of genetic variation within a population.

The neutral-mutation hypothesis does NOT suggest that: A) the evolution of most genetic variation in a population is influenced by genetic drift. B) when natural selection is at work on protein variants, it will lead to little variation in the population. C) most molecular variation is adaptively neutral—for example, most protein variants are functionally equivalent. D) natural selection is still an important evolutionary force. E) genetic variation in a population is maintained mainly by natural selection

E) genetic variation in a population is maintained mainly by natural selection

Which of the following does NOT bring about evolution in a population? A) small population size B) migration of individuals from a population with a different genetic structure C) mutation D) selection E) random mating

E) random mating

Antibodies are to Western blots as _____ is/are to Southern blots. A.RNA probes B.proteins C.DNA probes D.amino acids E.DNA or RNA probes

E. DNA or RNA probes

Recently, genome-wide association studies that locate genes influencing quantitative traits have been facilitated by the use of: A.pedigrees. B.controlled crosses. C.clonal lineages. D.RFLPs. E.SNPs.

E.SNPs.

Which of the following is NOT a reason that metagenomics is particularly useful for studying microbes? A.Many bacteria that cannot be cultured in the laboratory can now be studied. B.The composition of natural microbial communities can be reconstructed. C.The microbiome of individuals can be compared to understand the basis of disease. D.Previously unknown species of bacteria and new gene families have been discovered. E.The genomes of somatic cells in a human individual can vary significantly.

E.The genomes of somatic cells in a human individual can vary significantly.

What information CANNOT be learned from the structure of a protein? A.The location of the active site of an enzyme B.Possible interaction sites with other molecules C.Targets for potential drugs D.A source of insight into the function of an unknown protein E.The number of introns in the gene that encodes the protein

E.The number of introns in the gene that encodes the protein

Which of the following can be used for genetic engineering in plants? A.Ti plasmid B.Agrobacterium tumefaciens C.selectable markers D.Ti plasmids and Agrobacterium tumefaciens only E.Ti plasmids, Agrobacterium tumefaciens, and selectable markers

E.Ti plasmids, Agrobacterium tumefaciens, and selectable markers

In a normal distribution, 99% of the measurements fall within: A.1% of the mean. B.5% of the mean. C.plus or minus one standard deviation of the mean. D.plus or minus two standard deviations of the mean. E.plus or minus three standard deviations of the mean.

E.plus or minus three standard deviations of the mean.

Which of the following is a set of molecular techniques for locating, isolating, altering, and studying DNA segments? A.in situ hybridization B.gel electrophoresis C.molecular cloning D.Southern blotting E.recombinant DNA technology

E.recombinant DNA technology

True or False: The phenotype of a dominant allele is never seen in the F1 progeny of a monohybrid cross.

False

______________ can cause a single genotype to produce a wide range of potential phenotypes.

Environmental effects

A punnett square for a cross involving 2 genes (each with 2 alleles) has 4 rows and 2 columns.

False

True or False: Asexual reproduction will be selected in populations where genetic variation is needed for survival

False

Some organisms have multiple X and Y chromosomes and even different numbers of X and Y chromosomes. You have discovered such a species. Females have 8 X chromosomes, whereas males have 4 X and 2 Y. Describe the X and Y constitution of the gametes produced by this species—both male and female—that allows these chromosome numbers to be stably maintained.

Females must produce one type of gamete, with 4 X chromosomes, whereas males produce two types of gametes, with 4 X chromosomes or with 2 Y chromosomes. Fertilization using a 4 X male gamete produces an 8 X female, whereas fertilization with a 2 Y gamete produces a male.

Why do you think the mutation rate in immunological genes is unusually high?

For the immune system to serve its purpose, it continually strives to anticipate future threats by producing vast numbers of structurally diverse potential antigen-recognition sites. The immune system has in essence been "engineered" over evolutionary time to be a hypervariable system so that it can produce highly diverse populations of antigen-recognition sites for antigens that the organism hasn't even been exposed to. For example, the somatic recombination process that joins the V, J, D, and C gene segments in developing B cells has evolved to be imprecise and to involve random deletions or additions of several nucleotides at the junctions of the recombining segments.

In an effort to identify the influence of genetic factors on both Type 1 diabetes and Type II diabetes, researchers calculated concordance rates for monozygotic twins. Concordance rates of 30-50% have been found for Type I diabetes with concordance rates of 80% for Type II. For both kinds of diabetes, dizygotic concordance rates were about 15%. What does this information suggest concerning the relative effect of genetic and environmental factors for each type of diabetes?

Genetic influences exert a larger role in Type II diabetes than in Type I diabetes.

A deletion of a small region on the long arm of chromosome 15 causes a developmental disorder in children called Prader-Willi syndrome when the deletion is inherited from the father. However, the deletion of this same region of chromosome 15 can also be inherited from the mother, but this inheritance results in a completely different set of symptoms, called Angelman syndrome. What type of genetic phenomenon does this represent?

Genomic imprinting

Frankenstein tells Dracula that he thinks that fast-flying bats tend to suck blood faster than slow-flying bats do. Because flight speed is easier to measure than blood sucking is, Dracula considers how he might use this information in his breeding program. Could Dracula select on flight speed and get an increase in blood sucking? What information would Dracula need to be able to answer this question, and how might he determine this information?

He would need to demonstrate that there is a genetic correlation between flight speed and blood-sucking rate. He needs a measure of additive genetic variances for both traits in order to calculate and evaluate an additive genetic correlation.

In overdominance, the highest fitness is found in which genotype?

Heterozygote

Assume that freckles are caused by a dominant allele on an autosomal chromosome. A man has freckles but one of his parents does not have freckles. What is his genotype?

Heterozygous

What are homeotic genes and what do they do?

Homeotic genes play crucial roles in developmental processes in higher organisms by coding for regulatory proteins (e.g., transcription factors) that activate other genes that control segment-specific characteristics of body parts. Homeotic genes control the fate and ultimate development of body segments. Mutations in homeotic genes cause body parts to appear in the wrong segments of the body.

In most populations, there is fairly strong selection against albinism because albinos don't produce melanin, causing their skin cells not to be protected from the damaging effects of sunlight. Also, the lack of melanin in their eyes causes them to have poor eyesight. Finally, in most cultures albinos are seen as abnormal, and they are not normally sought out for marriage and mating. Therefore, in most populations the alleles that cause albinism are selected against, and they decrease in frequency or are kept at a low level, causing the recessive trait to be rare.

What is the function of cAMP in regulation of the lac operon?

It activates an activator protein

What is the apparent purpose for X inactivation in humans and other mammals?

It allows for the levels of expression of genes on the X chromosome to be similar in males and females.

Under what conditions would you expect optimal transcription of genes of the lac operon?

Low levels of glucose results in high concentrations of cAMP cAMP is the substrate that allows CAP to bind to the CAP site The CAP lac operon is transcribed when glucose levels are low, and bacteria are in need of an energy source (they utilize lactose) The repressor is then binded to allolactose so it lets go of the operator Therefore, a *low-glucose, high lactose, and high allolactose environment* would be ideal for the transcription of genes of the lac operon

What are morphogens, and what do they do?

Morphogens are proteins/RNA whose concentration gradients in a developing organism affect the developmental fate of the surrounding region.

What is true about the cell cycle in adults?

Most cells of the body are in G0

Explain the significance of telomerase in cancer cells in detail.

Most somatic cells normally do not express telomerase. Because of this, somatic cells normally can divide only a limited number of times (between 50-72 called the Hayflick limit)before the telomeres are completely removed and the chromosomes become unstable. This makes most normal somatic cells mortal.However, in most cancers, mutations occur that allow telomerase to be expressed. Because the telomeres are restored after replication, these cells are able to divide an unlimited number of times, allowing cancer cells to reproduce themselves without limit and allowing tumors to grow to large size and cancer to spread within the body and become immortal.

In the Hardy-Weinberg problem, a population of 100 individuals has the allele frequencies are p= 0.7 and q= 0.3. Using this information, we can conclude which of the following:

Nine individuals in this population are expressing the recessive phenotype.

When animals like Dolly the sheep are cloned using techniques that transfer a nucleus from a donor animal into the egg of a recipient animal, is the resultant clone genetically identical to the nuclear donor animal?

No. Although the clone will share identity with the donor animal for genes encoded by the nuclear genome, it will in contrast inherit its cytoplasmic genes (i.e., mitochondrial genes) from the egg donor.

What are Northern analyses used for? Describe the steps involved in performing a Northern analysis, and describe how levels of gene expression are determined.

Northern analyses are used to examine gene expression at the mRNA level. Steps are the following:(a) Isolate and purify RNA from cells.(b) Fractionate RNA using gel electrophoresis.(c) Blot the RNA to a solid support membrane (usually nylon).(d) Probe the membrane (containing blotted RNA) with a specific labeled sequence.(e) Wash the membrane to remove unbound probe.(f) Expose the membrane to film and develop an autoradiogram.Note that the higher the intensity of the signal, the greater the relative gene expression level.

What is true of comparing a genetic map to a physical map for a chromosome

On a genetic map, the region between two neighboring genes cannot exceed 50. The region near the centromere will be larger on a physical map than on a genetic map.

When a population is at Hardy-Weinberg equilibrium which one of the following is true? Allele frequencies change generation after generation. The population is a sink for immigrants. Individuals of like genotype are most likely to mate. Genotypic frequencies change generation after generation. One can calculate the recessive allele frequency directly from the homozygous recessive genotype.

One can calculate the recessive allele frequency directly from the homozygous recessive genotype.

Many good ideas in science ultimately turn out to be incorrect, and this has happened several times in the history of genetics. In your own words, state one idea in the history of genetics that turned out to be incorrect.

Pangenesis- The idea that information needed to encode each body structure is stored in that structure and transported to the reproductive organs and passed to the embryo at conception. Inheritance of acquired characteristics - The idea that traits acquired through use during one's lifetime can be passed to one's offspring. Preformationism - The idea that the sperm or egg carries a tiny preformed person whose development simply involves enlargement. Blending inheritance - The idea that the genetic material is a fluid that gets blended during sexual reproduction between a male and female, resulting in the production of traits in the offspring that are blended intermediates of those of the parents.

A normal chromosome A B C D * E F G H I J K has mutated to A B F E * D C G H I J K.This is an example of a _________________ chromosomal mutation. ( * denotes the centromere)

Pericentric inversion

How does epistasis differ from Mendel's principle of dominance?

Phenotypic expression is often the result of products produced by multistep metabolic pathways involving several different genes; each gene encodes an enzyme that regulates a specific biochemical step or event. Epistasis refers to the interaction among two or more genes that control a common pathway. For example, a mutation in any single gene contributing to a metabolic pathway can affect the expression of other genes in the pathway and, of course, the final phenotype, depending on which biochemical step that gene controls.Epistasis thus involves interaction among alleles located at different gene loci. This is in contrast to dominance, which involves interaction between alleles located at the same gene locus.

Aneuploidy is a change in the number of individual chromosomes. Which of the following is not an example of aneuploidy?

Polyploid

What is the mechanism that would cause a pure white flower to develop after adding an extra purple gene to a petunia. What is the name of this process? (2pts) Explain the process and how it works (be sure to include all proteins/enzymes).

RNA interference 2pt Double stranded RNA is recognized and destroyed by Dicer 2pts siRNAs are produced and combine with RISC (RNA-Induced Silencing Complex) Finds complementary RNA sequences and causes them to be broken down 2 pts RNA-induced transcriptional silencing (RITS) complex methylates purple gene 2 pts

Hair color is determined in a new breed of dog is coded for genes of alleles at the B and E loci. A dominant allele B encodes black pigment, whereas a recessive allele b encodes brown pigment. Alleles at a second locus affect the deposition of the pigment in the shaft of the hair; dominant allele E allows dark pigment (black or brown) to be deposited, whereas recessive allele e prevents the deposition of dark pigment, causing the hair to be yellow. What type of gene interaction does this represent?

Recessive epistasis

Round seeds (R) is dominant to wrinkled seeds (r), and yellow seeds (Y) is dominant to green seeds (y). A true-breeding plant with round and yellow seeds is crossed to a true-breeding plant with wrinkled and green seeds. What is the genotype of the F1 progeny?

RrYy

Women with Turner syndrome (XO) and normal women (XX) are clearly different phenotypically. In addition, the vast majority of XO conceptions abort before birth. However, both XO and XX women have one active X chromosome since the X in XO women remains active and one might expect that they would therefore have similar phenotypes. What is the most reasonable explanation for their different phenotypes?

Some genes remain active on the inactive X chromosome and XX women will have two copies of these genes expressed and XO women only one copy.

Garter snakes eat poisonous newts. Selection favors increased resistance to the poison. Garter snakes must also escape their own predators, and they do so by crawling away (fast snakes are more likely to escape than slow snakes are). After studying snakes for some time, you discover that (1) both resistance and speed are highly heritable and (2) selection on resistance and speed is strong. Nonetheless, you find that neither trait increases very much each generation. Explain this result.

Speed and resistance are probably negatively genetically correlated. Positive selection on one trait will cause a negatively genetically correlated trait to decrease. If both speed and resistance are selected to increase, this correlated negative response will dampen the response to selection in both traits.Note that the question states that both traits are highly heritable and under strong positive selection. Genetic variation should not be exhausted if the heritability is high.

The fruit fly Drosophila melanogaster is an important model system for studying inheritance in animals and genetic control of animal development, including humans. Evaluate fruit flies as a model system for human biology. What are their strengths and weaknesses as a model system?

Strengths-Fruit flies have proven to be an excellent model system for studying aspects of biology that they share with humans. Fruit flies are simpler in structure and physiology than humans and have a much simpler genome. They are small and easy to raise, they have a short generation time, and they produce a large number of offspring. Their chromosomes have been mapped and their genomes analyzed extensively. It is relatively easy to isolate and study mutants that are defective in specific processes of interest. These characteristics make them ideal for genetic studies of biological processes. Weaknesses - Some aspects of fruit fly genetics and development are not shared with Page 15 humans. Therefore, some features discovered in fruit flies will not apply directly to humans. Also, humans have many features that fruit flies lack. Fruit flies will not serve well as a model system for studying these features of human biology.

Compare the fields of structural, functional, and comparative genomics. What is the purpose of each?

Structural genomics is concerned with the actual base sequence of a genome and the organization of genes and other sequences. The purpose is to determine the sequence of a genome and produce maps that show the physical relationship between functional parts like genes, gene regulation elements, and centromeres.Functional genomics is concerned with the RNAs and proteins encoded by the sequences determined by the structural genomic studies. The purpose is to determine which parts of the genome encode RNAs and proteins as well as functions of each RNA or protein.Comparative genomics takes the information from structural and functional genomic studies of different organisms and compares the sequences and functional parts of the genomes. The purpose is to find motifs that are common to different organisms and to find divergences between similar organisms that can clarify their differences.

Suppose that a study of college students in Sweden estimates heritability of IQ to be 0.8. Based on this evidence, a school board in a struggling urban school district in the United States concludes that improving teaching methods and the physical conditions of schools is useless because intellectual achievement is determined almost entirely by genes and relatively little by the educational environment. Critique this conclusion based on your understanding of heritability.

Students might note that IQ should not be equated with intellectual achievement, but they must go further than that to demonstrate their understanding of heritability. The school board's decision is based on at least two major misconceptions about heritability. The first misconception is that estimates of heritability are universal, so that an estimate of heritability in one population can be used to estimate it in another population. In fact, an estimate of heritability only applies to the population that was measured in the study. A second major misconception is that high heritability indicates that the environment is not important to the trait of interest. In fact, a high heritability indicates only that there is relatively more genetic variance than environmental variance contributing to differences in the trait. If the environment is uniformly poor in the school district and there is at least some genetic variation, then heritability will be high. However, this does not mean that performance can't be improved by enriching the environment. Students might also note that the methods used to estimate heritabilities in humans are not very reliable and that any estimate should be interpreted with caution.

Predict the sexual phenotype of a person who is XY but whose Y chromosome carries a deletion of the SRY gene. Explain your prediction.

The SRY gene is the primary determinant of maleness in humans. If it is deleted, the gonads will not be induced to differentiate as testes, and the individual would likely follow the female developmental pathway. (Actually, this condition exists as Swyer syndrome. It turns out that the gonads do not develop into functional ovaries, indicating that genes other than the SRY also have roles in sexual differentiation. However, these individuals develop as apparently normal females until the lack of female hormones from the ovaries causes puberty not to be induced without hormone therapy.)

What are oncogenes and tumor-suppressor genes? How are they involved in carcinogenesis?

The control of the cell division cycle is regulated by stimulatory genes (oncogenes) and inhibitory genes (tumor-suppressor genes), and mutations in either type can lead to cancer by deregulating the cell cycle. Mutations in an oncogene can lead to an overactive cellular process, resulting in unregulated cellular proliferation. A defective tumor-suppressor gene can lead to the same result by blocking the activation of a critical "braking" process necessary for the appropriate control of cell-cycle progression.

Suppose that an apparently female athlete fails a gender test and is not allowed to compete in her event. The gender test is based on examination of cheek cells for the presence of one or more Barr bodies. Later, it is discovered that the athlete has androgen-insensitivity syndrome.Evaluate the decision of the officials to exclude the athlete from athletic competition as a female in light of your knowledge of androgen-insensitivity syndrome. Do you think the athlete should be allowed to compete as a female?

The decision to ban the athlete very likely was unfair. Other than the presence of testes and the absence of internal female reproductive structures, she is anatomically female. Although she has male hormones in her system, her muscle and other cells do not respond to the presence of the male hormones. Very likely, she does not gain a competitive advantage over other females by the presence of the Y chromosome, testes, and male hormones

You have learned that purple flowers are dominant to white in Mendel's peas. When walking the grounds of Mendel's monastery, you come across a stray purple pea plant. You suspect that it is descended from Mendel's experimental plants, but you have no idea of its exact heritage. Propose two ways that you could determine the plant's genotype with respect to the flower color. Assume that you have any other pea plants that you might want to use in your analysis. Provide expected results and interpretations of possible results for your experiments. Which of the two ways would be easier and why?

The easiest way would be to allow the plant to fertilize itself. If it produces only purple offspring, it must be PP. If it produces 3 purple:1 white, it must be Pp. This is easy because you don't have to do any manipulations. Another way would be to do a testcross of the unknown purple plant with a white tester (pp). If the plant is PP, then the offspring of this testcross would be all purple. If the unknown plant is Pp , then the offspring will be 1 purple:1 white. This is harder because you have to set up the crosses.

You have learned that purple flowers are dominant to white in Mendel's peas. When walking the grounds of Mendel's monastery, you come across a stray purple pea plant. You suspect that it is descended from Mendel's experimental plants, but you have no idea of its exact heritage. Propose a way that you could determine the plant's genotype with respect to the flower color. Assume that you have any other pea plants that you might want to use in your analysis.

The easiest way would be to allow the plant to fertilize itself. If it produces only purple offspring, it must be PP. If it produces 3 purple:1 white, it must be Pp. Another way would be to do a testcross of the unknown purple plant with a white tester (pp). If the plant is PP, then the offspring of this testcross would be all purple. If the unknown plant is Pp, then the offspring will be 1 purple:1 white.

Narrow-sense heritability for IQ scores has been estimated as 0.4. If the mean IQ score in the population is 100, what is the predicted IQ for a group of children whose parents had a mean IQ score of 150?

The selection differential in this example is 50 IQ units. If the narrow-sense heritability is 0.4, then the increase in IQ over the mean IQ score should be h2 × S = 0.4 × 50 = 20. The predicted IQ, given these assumptions, is 120.

DNA polymerase 3- adds nucleotides to the 3' end of the growing strand of DNA. (True or False)

True

Ligase- Joins adjacent DNA fragments (True or False)

True

True or False: A fruit that is 7N will most likely be larger than a 2N fruit.

True

True or False: A testcross can be used to determine whether an individual is homozygous or heterozygous.

True

True or False: Epigenetics explains changes in gene expression that can be altered by maternal nurturing

True

How has molecular data helped resolve the evolutionary relationships among distantly related taxa?

Trying to assess the evolutionary history of distantly related organisms is often difficult because the organisms have few characteristics in common. All organisms have certain molecular traits in common, such as ribosomal RNA sequences and some fundamental proteins. These molecules offer a valid basis for comparisons among all organisms.

A study was conducted to investigate the levels of calcium and growth hormone excreted in chicken dung on a major chicken farm. The variances (V) were calculated and are shown below. Variance . Calcium . Growth hormone VP 321.2 95.8 VE . 119.7 . 69.4 VA . 107.4 . 10.1 VD . 94.1 . 16.3 a. Calculate the narrow-sense heritability for both traits (calcium and growth hormone levels).b. Which trait, if any, will more likely respond to artificial selection?

VP = phenotypic varianceVA = additive varianceVD = dominance varianceVE = environmental variancea. For calcium: h2 = VA/VP = VA/(VE + VA + VD) = (107.4)/(119.7 + 107.4 + 94.1) = 0.334. For growth hormone: h2 = (10.1)/(69.4 + 10.1 + 16.3) = 0.105.b. Artificial selection will more likely alter calcium levels than growth hormone levels.

What is the role of the major histocompatibility complex (MHC) in tissue-graft rejection?

When tissues are transferred from one species to another, or from individual to individual within a species, the transplanted tissues are usually rejected by the host animal. Early studies demonstrated that this tissue-graft rejection is caused by an immune response that occurs when antigens on the surface of the grafted tissue are detected and attacked by T cells in the host organism. The antigens that elicit graft rejection are referred to as histocompatibility antigens, and they are encoded by a cluster of genes called the major histocompatibility complex (MHC). The MHC genes are highly variable genes, with more than 100 different alleles for some MHC loci. Because each individual possesses five or more MHC loci, and there are many possible alleles at each locus, no two individuals (with the exception of identical twins) produce the same set of histocompatibility antigens. The exceptional variation in histocompatibility antigens provides each individual with a unique identity for their own cells and allows the immune system to distinguish self from nonself. This variation in the MHC is also the cause of rejection in organ transplants.

What is the role of the major histocompatibility complex (MHC) in tissue-graft rejection?

Discuss the role of the availability of whole-genome sequences in understanding the evolutionary process.

Whole-genome sequences are providing new information about how genomes evolve and about the processes that shape the size, complexity, and organization of genomes. By examining different genes in a genome, we have been able to observe that exons of different genes have been exchanged, creating genes that are mosaics of other genes. Whole-genome sequences make apparent the duplication of individual genes, chromosomal segments, and even entire genomes. Genome sequences from different organisms also might provide evidence for horizontal transfer of genes.

The genetic code uses three bases to encode one amino acid. Why can't the code use only two bases to encode each amino acid?

With four bases in RNA, there are only 16 combinations of two bases. There are 20 different amino acids, so this would not be enough to encode all amino acids.

Most pedigrees showing the hypothetical human trait show the following characteristics: Females are affected twice as frequently as males. Affected fathers may have affected daughters but never affected sons. Half the children of affected mothers and normal fathers are affected. What is the most likely mode of inheritance for this disorder?

X-linked dominant

Is it possible for a trait to be discontinuous and yet determined by multiple genetic and environmental factors? Explain.

Yes, it is. These kinds of traits are described as meristic, meaning that they have a limited number of distinct phenotypes but are quantitative. As noted in the text, litter size in mice is a meristic trait. Other examples of meristic traits would be the number of bristles on fruit-fly abdomens and the number of eggs laid by sea turtles. In these cases, there are limited numbers of distinct phenotypes produced, but the specific phenotype ultimately expressed is controlled by multiple genes (i.e., is polygenic) and by environmental factors. Also, there are threshold traits. A threshold trait is discrete, but underlying the trait is a continuous distribution in a population of genetic and environmental risk associated with the trait that can be explained by multifactorial inheritance. If an individual exceeds a threshold value of risk, that individual will show the trait.

Do the principles discovered by Mendel for discontinuous traits also apply to the inheritance of traits that exhibit continuous variation? Explain your answer.

Yes. Over the 18-year period after Mendel's work was rediscovered, work by several eminent geneticists including Nilsson-Ehle, East, Johannsen, and Fisher demonstrated that the inheritance of quantitative characteristics could be explained by the cumulative (i.e., additive) effects of multiple genes, but the behavior of each gene was determined by Mendel's principles.

Evolution can be defined as

a change in the genetic makeup (allele frequency) of a population from one generation to the next.

What is one feature of meiosis that produces genetic variability in gametes? In two or three sentences, explain how this feature causes genetic uniqueness.

a. Independent assortment. In meiosis I—metaphase and anaphase—nonhomologous chromosomes distribute randomly. Alignment and separation of one pair of homologous chromosomes is independent of how a different pair separates. Different gametes that have different chromosomes can have different alleles for the same genes, so the gametes normally have different combinations of alleles. b. Crossing over- In meiosis I—prophase—portions of homologous chromosomes exchange, changing combinations of alleles of genes on a single chromosome, so not even sister chromatids are identical after crossing over. Each gamete has only one copy of each homolog, and each homolog now has a unique combination of alleles.

The table below shows narrow-sense heritability estimates for body weight and egg production in chickens. Trait. .h^2 Body weight. .0.5 Egg production. .0.2 a. Which chicken trait would respond best to selection? Explain your answer.b. Explain the expected gain if high-egg-producing chickens are selectively bred.c. Explain how and why the h2 would change over generations of selective breeding for high egg production.

a. The h2 value for body weight is higher, so it would respond better to selection than would egg production. The h2 indicates the proportion of variation in the population that is caused by difference in additive, selectable alleles. Because h2 is higher for body weight, that trait will respond better to selective breeding using parents with the desired trait.b. The h2 predicts that the expected response to selection will be 0.2. In other words, offspring of the chickens from lines with the highest egg production will differ from the nonselected population by 20%. The mean value of the offspring's population will be 20% higher than the mean value of the nonselected parent population.c. As the additive alleles that give high egg production are selected for, the selected population will become increasingly homozygous for additive alleles in their genotypes. h2 will decrease because less of the variance in the population will be caused by genotypic differences.

Two varieties—X (susceptible) and Y (resistant)—of eggplant were used to characterize the genetics of resistance to a necrotizing plant pathogen. Eight thousand plants from each variety were inoculated, and the average number of necrotic lesions produced per leaf was recorded. Variety X averaged 52 lesions per leaf, whereas variety Y averaged six lesions per leaf. The F1 progeny from a cross between variety X and variety Y plants averaged 21 lesions per leaf, with a standard deviation of 3.7. Of the F2 progeny, 8000 were again tested by inoculation, and a total of four plants produced were phenotypically similar to the original parental plants—two plants for each extreme (i.e., parental) phenotype. Overall, the F2 plants averaged 18 lesions per leaf with a standard deviation of 7.5.a. How many gene pairs control resistance to this pathogen?b. Determine the broad-sense heritability of resistance to this particular pathogen among the F2 plants, assuming that there is no genetic-environmental interaction variance for this trait.

a. Two of each extreme parental (P1) type plant were produced in the F2 progeny pool. The number of F2 progeny plants expressing either extreme phenotype = 2/8000 = 1/4000. Using the formula (1/4)n and solving for n: 1/4000 ≅ 1/4096 = (1/4)6, indicating that six gene pairs are involved in the pathogen resistance response.b. The broad-sense heritability (H2) represents the proportion of the phenotypic variance that is due to genetic variance and is calculated by dividing the genetic variance by the phenotypic variance: H2 = VG/VP. If there is not genetic-environmental interaction variance, then VP = VG + VE. Because the F1 plants have identical genotypes, we can use the variance in the F1 as an estimate of environmental variance. Therefore, VE = (3.7)2 = 13.69. Note that the phenotypic variance among the F2 = VG + VE = (7.5)2 = 56.25. Genetic variance among the F2 can be calculated as follows: VG = VP - VE = (56.25 - 13.69) = 42.56. Therefore, among the F2 plants, H2 = (42.56)/(56.25) = 0.757.

Two different varieties of pumpkin have the same mean fresh weight of 22.5 lb. However, one variety (LV) has a very low variance, while the other (HV) has a much higher variance in fresh weight.a. What are some possible reasons for the differences in the variance between these two varieties?b. If you were a pumpkin breeder and wanted to develop a heavier variety of pumpkin, which of these two varieties would you select to start your breeding program? Explain why.

a. VP = VG + VE + VGE. Assuming that the two varieties are grown in the same environment, differences in phenotypic variance could be explained by (i) differential effects of various environmental factors on the different varieties (the varieties have different values of VGE), or (ii) inherent genetic differences between the varieties (the varieties have different values of VG). For example, the variety with higher weight variance may be more genetically diverse.b. In some cases, the variety with higher variance may be better because more variation in weight range would be represented in the progeny; thus, there would be more likelihood of finding significantly heavier individuals to select out. Note, however, that if you choose to start with the higher variance variety (HV), you would hope that a major proportion of the variance in weight observed was due to genetic variation. On the other hand, it is often beneficial to produce progeny with uniform phenotypes. If uniformity has high importance, then the pumpkin variety exhibiting less variance (LV) may be the better one to start with.

Gel electrophoresis can be used to separate DNA on the basis of

size and charge

There are five conditions that must be met for a population to be in Hardy-Weinberg equilibrium. Which of the following is not one of those conditions?

non-random mating

A human tetragametic chimera would

not have a DNA paternity or maternity test always accurately determine if they are a child's real biological parent.

The frequency of a particular allele within a population can be changed, over time, by

selection

Autosomal traits that appear mostly in one sex are:

sex influenced

What would the phenotype be a female who is heterozygous for an X linked dominant trait?

she would express it in a mosaic pattern

In poodles, black fur is dominant to white fur. A black poodle male is crossed with a white poodle female. In a litter of four, all of the puppies are black. What is the best conclusion?

the parents male is homozygous

The SRY gene on the human Y chromosome codes for

the testis determining factor, a key product that results in "maleness"

what is a crossover?

when chromosomes exhange genetic information with each other

The map distances for genes that are close to each other are more accurate than map distances for genes that are quite far apart because

with genes that are far apart, double crossovers and other multiple-crossover events often lead to nonrecombinant or parental offspring and thus reduce the true map distance.

The two major components of fitness of a genotype are

viability and fertility

In a population of 1000 baby kitties, 40 are white because of a recessive allele (b). Non-white cats are either homozygous dominant (BB) or heterozygous dominant (Bb). What is the frequency of heterozygous kitties in the population?

0.32

Describe two different ways Retinoblastoma may develop.

The tRNA for a start codon has which of the following anticodons?

5'- CAU - 3'

If the sequence of an RNA molecule is 5'-GGCAUCGACG-3', what is the sequence of the nontemplate strand of DNA?

5'-GGCATCGACG-3'

Suppose that the "fabulous" phenotype is controlled by two genes, A and B. Allele A produces enough enzyme 1 to convert "plain" to "smashing." Allele a produces no enzyme 1. Allele B produces enough enzyme 2 to convert "smashing" to "fabulous." Allele b produces no enzyme 2. The A and B genes are both autosomal and assort independently. What will be the expected ratio of the F2 offspring of the F1 generation?

9 "fabulous": 3 "smashing": 4 "plain"

Which statements are correct when describing substitution mutations?

A transversion is the substitution of a pyrimidine for a purine or of a purine for a pyrimidine. A transition is the substitution of a purine for a purine or of a pyrimidine for a pyrimidine. Transversion mutations include A-->C. They can lead to nonsense (stop codon), missense (wrong amino acid) mutation and silent mutations (same amino acid).

A) Briefly describe PCR and B) list what are the necessary components to run a PCR reaction?

A)There are three main stages: Denaturing - when the double-stranded template DNA is heated to separate it into two single strands. Annealing - when the temperature is lowered to enable the DNA primers to attach to the template DNA. Extending - when the temperature is raised and the new strand of DNA is made by the Taq polymerase enzyme. [A solution containing a DNA sample is denatured at 90-100 degrees Celcius, then cooled to 30-65 degrees C to allow primers to anneal to contemporary sequences. It is then heated to 60-70 degrees C to create two new DNA molecules. Each time the PCR reaction is run, the amount of DNA doubles.] B)DNA template, Taq polymerase, primers and DNA replication enzymes, nucleotides

In humans, blood types A and B are codominant to each other and each is dominant to O. What blood types are possible among the offspring of a couple of blood types AB and A?

A, B, and AB only

A mother of blood type A gives birth to a child with blood type O. Which of the following could NOT be the blood type of the father?

The anticodon 5' GGC 3' corresponds to which amino acid?

Alanine

A section of a genome is cut with three enzymes: A, B, and C. Cutting with A and B yields a 10kb fragment. Cutting with B and C yields a 2kb fragment. What is the expected result from a digest with A and C, if the C site lies in between the A and B sites

An 8Kb fragment

You are studying body color in an African spider and have found that it is controlled by a single gene with four alleles: B (brown), br (red), bg (green), and by (yellow). B is dominant to all the other alleles, and by is recessive to all the other alleles. The bg allele is dominant to by but recessive to br. You cross a pure-breeding brown spider with a pure-breeding green spider. Predict the genotype of the progeny.

B.bg

Piebald syndrome

Can cause both mice and humans to have the same white patch on their stomach and forehead resulting from a mutation in the same gene

Transformation

DNA present in the medium is taken up by the bacteria

Most activators stimulate mRNA synthesis by binding to the

Enhancers

You examine are studying a new disease where the individuals who have this disease are missing one essential protein required for a metabolic process. You isolate the gene responsible for this disease and notice that there is no mutation in the triplet sequence in the region that codes for the protein's codons. How is this possible?

Epigenetic changes, methylation, mutation in the promoter gene, or epistasis and gene interactions.

Eye color has a concordance of 0.99 in monozygotic twins. What does this say about this trait?

Eye color has a strong genetic component AND most identical twins will have the same eye color

True or False: A kozak sequence is found on bacterial mRNA.

False

True or False: Fragile X syndrome has fragile sites that are heavily acetylated.

False

True or False: Fragile X syndrome would show a pedigree like that of Huntington Disease.

False

True or False: Modern wheat, Triticum aestivum, is a sterile hybrid.

False

True or False: Of the possible chromosomal aneuploidy seen in humans, there are more syndromes seen as monosomies than as trisomies.

False

True or False: Polyploidy is the presence of one or more chromosomes

False

True or False: Radiation from X rays causes T-T dimers to form in DNA because of its high energy, this leads to frameshift mutations.

False

True or False: Transposable elements are the same thing as retroviruses.

False

True or False: Transposable elements cause most DNA mutations in humans.

False

Reporter genes are

Genes that produce products that are easy to detect and/or quantify; can be inserted next to a "gene of interest" and expression of the "gene of interest can be followed throughout development"

Telomerase activity is most likely to be found in which cells in humans?

Germ line cells.

How do you know if genes are in a cis or trans configuration?

If genes are linked and the DOMINANT alleles are together on the same chromosome, then the configuration is CIS. This is shown on the example (a) on the left. Both of the dominant alleles are located on the same chromosome. When the genes are in cis configuration, the offspring will all almost look like the parental. This is how you can also tell the genes were at cis configuration. Now, if the dominant linked genes are across on the same chromosome, then the configuration is TRANS. This is seen in the example (b). Trans configuration shows the dominant alleles across from each other. When this happens, most of the offspring will be NEW and DIFFERENT form the parental.

Which one of the following topic of research belongs to the discipline of transmission genetics?

Inheritance pattern of gene alleles

List some facts about modern wheat, Triticum aestivum.

It is a hexaploid It is 6n=42 It is derived from three different species

What is the function of helicase?

It is an enzyme that unzips DNA during DNA replication

Polyploid facts:

Many 3N fruits are seedless - odd ploidy numbers cause the formation of unbalanced gametes during meiosis. Autopolyploids can occur during meiosis or mitosis. Alloploidy form a hybrid species because chromosomes from 2 species come together.

How are polygenic traits different from multifactorial traits? Give an example of each.

Polygenic traits: phenotype is determined by two or more gene pairs; a wide range of differences can be found in a population - most individuals are "average" (an example is skin color) [Professor's Answer: Polygenic: skin and hair color - trait is determined by two or more gene pairs] Multifactoral traits: phenotype is determined by more than one gene (inherited in Mendelian fashion) and environmental factors (example from the lecture: height is affected by multiple genes as well as nutrition) [Professor's Answer: Multi-factorial-means many factors (genes and environment effect the expressions of that gene): height, spina bifida, tree height - trait is controlled by more than one gene and affected by environmental factors]

Briefly describe how retroviruses violate the central dogma of biology.

Retroviruses have an enzyme called reverse transcriptase which use RNA as a template to make DNA so instead of following the dogma of biology (DNA transcribed to RNA and RNA translated to proteins) , the RNA template makes DNA for the virus and enters the genome so the virus DNA is in your regular DNA, not following the way it is supposed to be.

Which sequences are only found in prokaryotes?

Shine-Dalgarno sequences

What might be found on a typical bacterial mRNA?

Start codon Terminator sequence Shine delgarno sequence Stop codon

Which of the following about sex chromosomes is true?

The X chromosome contains genetic information necessary for both sexes

The allele that causes achondroplasia is a recessive lethal allele.

True or False: Fragile X syndrome is caused by a CGG repeat.

True

True or False: Human aneuoploids can be detected through a karotype.

True

True or False: Temperate phages can undergo either the lytic or lysogenic cycle

True

True or False: Transposable elements can alter kernel color.

True

Conjugation

Two bacteria next to each other share information

Why does X-inactivation occur and in which sex does it occur in humans?

X inactivation occurs in the female sex and it occurs because one X gene must be basically turned off or else females would have twice as much genes of the X chromosome. Specifically, it is also necessary in order to ensure that males and females express the same amount of gene product

The stop codon UAA calls for

a release factor

In a certain species of plant, flowers occur in three colors: blue, pink, and white. A pure-breeding pink plant is mated with a pure-breeding white plant. All of the F1 are blue. When the blue F1 plants are selfed, the F2 occur in the ratio 9 blue:3 pink:4 white. a. How many gene pairs control the flower color phenotype? (2 pt) b. What is the name for this type of interaction (be VERY specific for full credit)? (2 pt) c. What is the genotype of the pink parent? (Use symbols of your own choosing.) (1 pt) d. What is the genotype of the white parent? (1 pts) e. What is the genotype of the F1 plants? (1 pts) f. What are the genotypes and associated phenotypes in the F2? (2 pts) g. Propose a biochemical pathway showing intermediates in the pathway leading to the synthesis of pigment(s) and clearly indicating which steps are controlled by each gene. (2 pts)

a. The 9:3:4 ratio observed in the F2 generation indicates a modification of the 9:3:3:1 ratio seen in a Mendelian dihybrid cross. This explains two gene pairs being involved, and the modification to 9:3:4 indicates recessive epistasis. b. Recessive epistasis happens when two alleles are required to express a trait (in this case, blue - it needs to have a B_W_ genotype). c. bbWW d. BBww e. BbWw f. In order to express blue, both dominant alleles must be present - if either gene is homozygous recessive, the phenotype of the flower is pink [bbW_] or white [B_ww]). g. Finally, a biochemical pathway that would explain this sort of inheritance pattern would be that a plant that is homozygous recessive for the white gene (B_ww) lacking a pigment making protein resulting in "albino" flowers. If a plant is heterozygous for the white gene and has a functional pigment protein, then B_ W_ would be blue, which is dominant, and bbW_ would be pink, which is recessive.

Which of the following should lead to apoptosis?

bax-bax homodimers

In a population, 8% of males have an X-linked recessive trait. How many females would have the phenotype for this X-linked recessive trait?

less than 1%

In birds, the homogametic sex is

male

A fly with genotype XXX would be phenotypically

metafemale

Which of the following is a process whereby cancer cells travel to other sites in the body and establish secondary tumors?

metastasis

In the endangered African watchamakallit, the offspring of a true-breeding black parent and a true-breeding white parent are all gray. When the gray offspring are crossed among themselves, their offspring occur in a ratio of 1 black : 2 gray : 1 white. Upon close examination of the coats, each hair of a gray animal is gray. What is the mode of inheritance?

one gene pair with incomplete dominance

During mitosis

sister chromatids are separated

The Philadelphia chromosome is a common cause of chronic myelogenous leukemia (CML) and is caused by a

translocation between chromosome 9 and 22

David and Peggy have a baby boy named Peter. The baby boy is born with the disease ultradorkitis. David and Peggy do not express the disease. Peggy's father expresses the disease while David's parents were tested and don't have it. What is the mode of transmission of this disease?

x-linked recessive

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