Exam 1 (Chap. 1)
Who, along with Alfred Wallace, formulated the theory of natural selection?
Charles Darwin
What significant genetic function occurs in the S phase of the cell cycle?
DNA synthesis
What is the central dogma of genetics?
DNA →RNA → protein
Cells that are metabolically active, but not destined to proliferate are said to be in _______.
G0 phase
During which stage can cells either exit the cell cycle or become committed to completing the cell cycle?
G1
Which of the two crosses shows a greater amount of deviation from the expected values?
The cross with the larger χ2 value.
The stage at which "sister chromatids go to opposite poles" immediately follows which of the stages listed below?
mitotic metaphase and metaphase of meiosis II
Organisms that are well understood from a scientific standpoint and are often used in basic biological research are often called ________.
model organisms
How many degrees of freedom (df) are there for each χ2 tested?
1
If a typical somatic cell has 64 chromosomes, how many chromosomes are expected in each gamete of that organism?
32
What is the χ2 value for cross (a)?
0.21
Tightly curled hair is caused by a dominant autosomal gene in humans. If a heterozygous curly-haired person marries a person with straight hair, what phenotypes (and in what proportions) are expected in the offspring?
1 curly : 1 straight
Polydactyly is expressed when an individual has extra fingers and/or toes. Assume that a man with six fingers on each hand and six toes on each foot marries a woman with a normal number of digits. Having extra digits is caused by a dominant allele. The couple has a son with normal hands and feet, but the couple's second child has extra digits. What is the probability that their next child will have polydactyly?
1/2
The autosomal (not X-linked) gene for brachydactyly, short fingers, is dominant to normal finger length. Assume that a female with brachydactyly in the heterozygous condition is married to a man with normal fingers. What is the probability that their first child will have brachydactyly?
1/2
Dentinogenesis imperfecta is a rare, autosomal, dominantly inherited disease of the teeth that occurs in about one in 8000 people (Witkop 1957). The teeth are somewhat brown in color, and the crowns wear down rapidly. Assume that a male with dentinogenesis imperfecta and no family history of the disease marries a woman with normal teeth. What is the probability that their first two children will have dentinogenesis imperfecta?
1/4
Albinism, lack of pigmentation in humans, results from an autosomal recessive gene (a). Two parents with normal pigmentation have an albino child. What is the probability that their next three children will be albino?
1/64
What is the χ2 value for cross (b)?
14.79
Mendel's Law of Segregation is supported by a ________ testcross ratio.
1:1
What genotypic ratio is expected? ___ Ww : ___ ww Enter your answer as numbers separated by a colon.
1:1
What phenotypic ratio is expected? ___ round : ___ wrinkled Enter your answer as numbers separated by a colon.
1:1
Which types of phenotypic ratios are likely to occur in crosses when dealing with a single gene pair for which all the genotypic combinations are of equal viability?
1:1, 3:1
The ant, Myrmecia pilosula, is found in Australia and is named bulldog because of its aggressive behavior. It is particularly interesting because it carries all its genetic information in a single pair of chromosomes. In other words, 2n = 2. (Males are haploid and have just one chromosome.) Which of the following figures would most likely represent a correct configuration of chromosomes in a metaphase I cell of a female?
2 x lined up in center
If there are 400 progeny total, what are the expected (theoretical) numbers of progeny in each phenotypic class? Enter your answer as a single whole number.
200
The diploid chromosome number of an organism is usually represented as 2n. Humans have a diploid chromosome number of 46. What would be the expected haploid chromosome number in a human?
23
What is the expected value of white flowers?
232.25
The house fly, Musca domestica, has a haploid chromosome number of 6. How many chromatids should be present in a diploid, somatic, metaphase cell?
24
If the first three F2 offspring grown from the cross described above are round, what is the probability that the next F2 offspring will be wrinkled?
25%
If one is testing a goodness of fit to a 9:3:3:1 ratio, how many degrees of freedom would be associated with the Chi-square analysis?
3
Round (R) seed shape is dominant to wrinkled (r) seed shape in pea plants. If an RR plant is crossed with an rr plant, what is the frequency of phenotypes in the F2 generation?
3 round sees, 1 wrinkled seed
Which DNA template below encodes the DNA sequence 5-GACCTC-3?
3'-CTGGAG-5'
Which DNA coding strand below would be associated with the mRNA 3'-GCAUGC-5'?
3'-GCATGC-5'
Assuming a typical monohybrid cross in which one allele is completely dominant to the other, what ratio is expected if the F1s are crossed?
3:1
Suppose that one of the normal children from Part B and one of the albino children from Part C become the parents of eight offspring. What would be the expected number of normal and albino offspring?
4 normal; 4 albino
If translation begins with the first start codon in the mRNA below, the second codon would be which of the following? 3'TCGGAUGCACUUGACAAUCCGUAGAC-5'
5'-CCU-3'
A recessive allele in dogs causes white spots. If two solid colored dogs are mated and produce a spotted offspring, what is the percentage chance their next puppy would be solid colored?
75%
What is the expected value of full pods? Remember that expected values do not have to be whole numbers.Express your answer to two decimal points (example: 100.00).
885.75
Mendel crossed peas having round seeds and yellow cotyledons (seed leaves) with peas having wrinkled seeds and green cotyledons. All the F1F1 plants had round seeds with yellow cotyledons. Diagram this cross through the F2F2 generation, using the Punnett square method. Notice that a dash ( _ ) is used where (because of dominance) it makes no difference as to the dominant/recessive status of the allele.
9/16 W_G_round seeds, yellow cotyledons 3/16 W_gground seeds, green cotyledons 3/16 wwG_wrinkled seeds, yellow cotyledons 1/16 wwggwrinkled seeds, green cotyledons
Which types of phenotypic ratios are likely to occur in crosses when dealing with two gene pairs for which all the genotypic combinations are of equal viability?
9:3:3:1
What is CRISPR-Cas?
A DNA editing complex isolated from bacteria that has been used to repair genes in multiple living organisms.
Drag the name of the appropriate stage of meiosis to the target above each diagram. Then, in the target of Group 2 below each diagram, specify whether the event of crossing over is possible or impossible/unlikely during this phase of meiosis. Note that the diagrams are in no particular order.
A. Anaphase II; Impossible or unlikely B. Metaphase II; Impossible or unlikely C. Prophase I; possible D. Metaphase II; Impossible or unlikely *Crossing over occurs during early prophase I when homologous chromosomes loosely pair up along their lengths. Crossing over occurs only between nonsister chromatids within a homologous pair of chromosomes, not between the sister chromatids of a replicated chromosome. Crossing over is reduced near the centromere; segments that are not adjacent to the centromere (for example, segments near the ends of chromosomes) are more likely to cross over.*
If an F2 generation from a self-cross always yields offspring in a 3:1 phenotypic ratio, which of the following P crosses could have occurred?
AA x aa
Two normal parents have five children, four normal and one albino. What are the most likely genotypes of the parents?
Aa x Aa
Which of the following is TRUE about alleles?
An allele is a variant form of a gene.
Which of the follow could occur if a cell cycle checkpoint was missed?
An unreplicated chromosome could be put through mitosis.
Which of the following is true?
Assume that a Chi-square test was conducted to test the goodness of fit to a 3:1 ratio and that a Chi-square value of 2.62 was obtained. The null hypothesis should be accepted.
The research of the following scientist(s) was instrumental to prove that DNA is the carrier of Genetic information in bacteria:
Avery, MacLeod and McCarty
________ is a discipline involved in the development of both hardware and software for processing, storing, and retrieving nucleotide and protein data.
Bioinformatics
In what ways is sample size related to statistical testing?
By increasing sample size, one increases the reliability of the statistical test and decreases the likelihood of erroneous conclusions from chance fluctuations in the data.
Early in the twentieth century, Walter Sutton and Theodor Boveri noted that the behavior of chromosomes during meiosis is identical to the behavior of genes during gamete formation. They proposed that genes are carried on chromosomes, which led to the basis of the ________.
Chromosome Theory of Inheritance
Two different matings were made between black members of the F2 generation with the following results. Cross Offspring Cross 1 All black Cross 2 ¾ black, ¼ white Label the genotypes of the parents and offspring in these two crosses. (Note that the offspring shown represent ratios of a large number of offspring, not just four individuals.) Use blue labels for the parents' genotypes. Use pink labels for the offsprings' genotypes. Labels can be used once, more than once, or not at all.
Cross 1: WW x WW all WW Cross 2: Ww x Ww WW, Ww, and ww
How could the botanist best determine whether the genotype of the green-pod plant is homozygous or heterozygous?
Cross the green-pod plant with a yellow-pod plant.
During interphase of the cell cycle, ________.
DNA content essentially doubles
The parent cell that enters meiosis is diploid, whereas the four daughter cells that result are haploid. Which statement correctly describes how cellular DNA content and ploidy levels change during meiosis I and meiosis II? (Note: Ignore any effects of crossing over.) View Available Hint(s)
DNA content is halved in both meiosis I and meiosis II. Ploidy level changes from diploid to haploid in meiosis I, and remains haploid in meiosis II.
Which of the following is the function of DNA?
DNA is responsible for the storage and replication of genetic information.
What is segregation?
During gamete formation, allele pairs are separated to form haploid gametes.
The longest stage of interphase is G2.
False
When cells withdraw from the continuous cell cycle and enter a "quiescent" phase, they are said to be in what stage?
G0
Checkpoints are points between phases of the cell cycle at which a cell determines whether all the requirements necessary for each phase of the cell cycle have been properly satisfied. For example, because a cell with damaged DNA can lead to cancer if it is allowed to divide, a cell with damaged DNA usually arrests the cell cycle until the damage can be repaired. At which phase(s) of the cell cycle would a cell normally check for the integrity of its DNA?
G1/S and G2/M phases
Given the state of knowledge at the time of the Avery, MacLeod, and McCarty experiment, why was it difficult for some scientists to accept that DNA is the carrier of genetic information?
Genes possess a variety of functions. Since proteins can contain up to 20 different amino acids, while DNA is made up of only four different nucleotides, proteins should have more functional variations. It seemed likely that proteins should be the genetic material.
Contrast chromosomes and genes.
Genes take part in the production of proteins through the processes of transcription and translation. They are the functional units of heredity. Chromosomes carry genes and take part in cell division during mitosis and meiosis.
Which individuals could be only heterozygous (Aa)? Select all that apply.
I-1 I-4 II-4 IV-1 IV-7
How is genetic information encoded in a DNA molecule?
Genetic information is encoded in DNA by the sequence of bases.
The research of the following scientist(s) was instrumental to prove that DNA is the carrier of Genetic information in viruses:
Hershey & Chase
Which unaffected individuals could possibly be either homozygous or heterozygous (A_)? Select all that apply.
II-8 III-1 III-5
Which of the following would be true of a plant heterozygous for a single gene controlling flower color? (Assume complete dominance).
If crossed with another heterozygous plant, the majority of progeny will have the dominant flower color.
What is the chromosome theory of inheritance?
It states that inherited traits are controlled by genes residing on chromosomes that are transmitted by gametes.
What is the chromosome theory of inheritance? (b) How is it related to Mendel's findings?
It states that inherited traits are controlled by genes residing on chromosomes that are transmitted by gametes.
Describe Mendel's conclusions about how traits are passed from generation to generation.
Mendel hypothesized that traits in peas are controlled by specific unit factors. He suggested that unit factors occur in pairs and that unit factors separate from each other during gamete formation.
Which of the following evolutionary processes generally increases genetic diversity in a population?
Mutation
Of the methods listed below, which would be the best way to determine which of two alleles of a gene is dominant to the other?
Observe the relevant phenotype in the progeny that result from a cross between individuals from two different pure-breeding lines.
In the genetic code a single codon may specify as many as ____ different amino acids.
One
Assume that in a series of experiments, plants with round seeds (W) were crossed with plants with wrinkled seeds (w) and the following offspring were obtained: 220 round and 180 wrinkled. What is the most probable genotype of each parent?
One parent is ww, the other is Ww.
During which stage of prophase I does crossing over take place?
Pachynema
Which condition is evaluated at the G2/M checkpoint?
Precise replication of DNA
Which of the following molecules serves the function to express the genetic material by being translated to protein?
RNA
In the 1970s, this discovery revolutionized DNA technology:
Restriction enzymes
Which part of interphase does DNA duplication take place?
S
What is the arrangement of chromosomes during metaphase?
Sister chromatids align along the equatorial plane of the cell.
Which of the following is true about the second meiotic division?
Sister chromatids are pulling apart.
How did Mendel's work support the chromosomal theory of inheritance?
The behavior of chromosomes during meiosis, as observed under a microscope, correlated with Mendel's principles of inheritance.
Which of the following statements about meiosis is true?
The chromosome number is reduced by one-half.
How is it related to Mendel's findings?
The chromosome theory of inheritance is based on the parallels between Mendel's model of heredity and the behavior of chromosomes during meiosis.
If somebody knew that a devastating late-onset inherited disease runs in his or her family (in other words, a disease that does not appear until later in life) and he or she could be tested for it at the age of 20, should the person find out whether he or she is a carrier?
The person should make a decision him- or herself and the decision may change depending on his or her age and other factors.
In humans, what is a fundamental difference between the production of female gametes and male gametes?
The production of female gametes but not male gametes involves an unequal division of cytoplasm.
The results of two of Mendel's crosses are shown. You want to calculate the χ2χ2 value and determine the p value for both crosses. What is the null hypothesis to be tested using χ2χ2 analysis?
There is no difference between the observed values and expected values for a monohybrid cross; the data fits a 3:1 ratio.
Which statement best describes the "central dogma" of genetics?
There is sequential transfer of information, residue by residue, in biomolecules. DNA →RNA→protein
Which of the following is true about sex-determining chromosomes?
They act like homologous chromosomes during meiosis so each gamete will get one sex chromosome.
Which of the following are true about codons?
They are complementary to DNA and specify amino acids at the ribosome.
A tetrad is composed of one pair of homologous chromosomes at synapsis of prophase I.
True
In an individual that is heterozygous for a particular trait, expression of the recessive allele is masked.
True
The 3:1 phenotypic ratio observed among progeny of an F1 X F1 cross requires random union of gametes.
True
A certain type of congenital deafness in humans is caused by a rare autosomal dominant gene. In a mating involving a deaf man and a deaf woman, could all the children have normal hearing?
Yes, assuming that the parents are heterozygotes (because the gene is rare), it is possible that all of the children could have normal hearing.
A cross between two individuals with different phenotypes that resulted in approximately 50% of each type of offspring would indicate the cross was ________.
a heterozygous dominant crossed to a homozygous recessive
What is a homunculus?
a sperm or egg containing a miniature adult, perfect in size and proportion
Which of the following is a good example of a mutant?
a white-eyed Drosophila
A __________ chromosome has its centromere located very close to, but not on, the end of the chromosome.
acrocentric
Which chromosome has a telomere but the p arm is much shorter than the q arm?
acrocentric
Name the bases in DNA and their pairing specificities.
adenine:thymine, guanine:cytosine
Assume that a black guinea pig crossed with an albino guinea pig produced 5 black offspring. When the albino was crossed with a second black guinea pig, 4 black and 3 albino offspring were produced. What genetic explanation would apply to these data?
albino = recessive; black = dominant
Which of Mendel's postulates were demonstrated? Unit factors exist in pairs. Unit factors separate from each other during gamete formation. Unit factors have dominance/recessive relationships.
all of the above
What will be the phenotype of the offspring if two F2 white guinea pigs are mated?
all white
Alternative forms of a gene are called ________.
alleles
The centromere of a chromosome separates during ________.
anaphase
Assuming no crossing over between the gene in question and the centromere, when do alleles segregate during meiosis?
anaphase I
During meiosis, chromosome number reduction takes place in ________.
anaphase I
When do sister chromatids separate during meiosis?
anaphase II
The accompanying sketch depicts a cell from an organism in which 2n = 2 and each chromosome is metacentric. Which of the following is the correct stage for this sketch?
anaphase of meiosis II
Which of the following are the areas where chromatids intertwine during meiosis?
chiasma
Name two cellular organelles, each containing genetic material, which are involved in either photosynthesis or respiration.
chloroplasts and mitochondria
Due to advances in biotechnology, all but which of the following has become commonplace?
cloning of human embryos
Of the following characteristics, which is least important for a species to possess in order for it to serve as a model organism?
close evolutionary relationship to humans
A fundamental property of DNA's nitrogenous bases that is necessary for the double-stranded nature of its structure is ________.
complementarity
What conditions are likely to apply if the progeny from the cross AaBb × AaBb appear in the 9:3:3:1 ratio?
complete dominance, independent assortment, and no gene interaction
You have identified a plant in your garden with a new flower color. You want to determine if this phenotype is dominant or recessive. Which cross would tell you this?
crossing the plant to one you know has the recessive trait
Which of the following groups of scientists were influential around the year 1900 in setting the stage for our present understanding of transmission genetics?
deVries, Correns, Tschermak, Sutton, Boveri
In many species, there are two representatives of each chromosome. In such species, the characteristic number of chromosomes is called the ________ number. It is usually symbolized as ________.
diploid; 2n
Which of the following contains all the others?
double helix
CRISPR-Cas has the potential to_____.
edit mutations in the human genome to cure genetic diseases
What is another term for a biological catalyst?
enzyme
Living organisms are categorized into two major groups based on the presence or absence of a nucleus. What group is defined by the presence of a nucleus?
eukaryotic organism
Electron microscopy of metaphase chromosomes demonstrated various degrees of coiling. What was the name of the model that depicted this process?
folded-fiber
The functional unit of heredity is a _______.
gene
The ________ consists of a linear series of three adjacent nucleotides present in mRNA molecules.
genetic code
What term is applied to a variety of projects whereby genome sequences are deposited in databases for research purposes?
genomics
Which two genotypes in an individual would be expressed as the same phenotype in a diploid organism?
homozygous dominant and heterozygous
What information can be obtained from a human pedigree?
how a gene is inherited
What would happen if, during meiosis, the chromosome number was not halved before egg and sperm formation?
in each successive generation, the offspring would double their chromosome number
In a Chi-square test, as the value of the χ2 increases, the likelihood of rejecting the null hypothesis ________.
increase
Which of Mendel's postulates can only be demonstrated in crosses involving at least two pairs of traits?
independent assortment
Genetics is the study of ________.
inheritance and variation
The chromosomal theory of inheritance_____.
is that genes for phenotypic traits are carried on chromosomes
A protein's shape and chemical behavior are determined by ________.
its linear sequence of amino acids
Suppose that the botanist carried out the test cross described in Parts A and B and determined that the original green-pod plant was heterozygous (Gg). Which of Mendel's findings does her test cross illustrate?
law of segregation
A normal male and an albino female have six children, all normal. What are the most likely genotypes of the parents?
male: AA; female: aa
A normal male and an albino female have six children, three normal and three albino. What are the most likely genotypes of the parents?
male: Aa; female: aa
During which part of meiosis (meiosis I or meiosis II) do the two alleles of a gene separate? During which phase does the separation occur? (Assume no recombination.)
meiosis I, anaphase
After meiosis II, ________ would be formed.
monads
The haploid number of a species is _______.
n
Can the deviation of observed values from expected values in cross (b) be attributed to random chance?
no
What are the basic subunits of DNA and RNA?
nucleotides
The Chi-square test involves a statistical comparison between measured (observed) and predicted (expected) values. One generally determines degrees of freedom as ________.
one less than the number of classes being compared
Label the genotypes of the parents (P1) and two offspring generations (F1 and F2). Labels can be used once, more than once, or not at all.
p1: WW x ww f1: Ww F2: W_ W_ W_ ww
What term is used to describe the fact that different genes in an organism often provide differences in observable features?
phenotype (physical)
Which if the following is not a source of genetic variation in meiosis?
polar body formation
In studies of human genetics, usually a single individual brings the condition to the attention of a scientist or physician. When pedigrees are developed to illustrate transmission of the trait, what term does one use to refer to this individual?
proband
The study of the set of proteins present in a cell is referred to as _______.
proteomics
What is the most likely mode of inheritance for this trait?
recessive
Which term describes meiosis I?
reducational
Recombinant DNA technology is dependent on a particular class of enzymes, known as ________ that cuts DNA at specific nucleotide sequences.
restriction enzymes
The nucleolus organizer region (NOR) is responsible for production of what type of cell structure?
ribosome
Which of the following cell structures is directly involved in protein synthesis?
rough endoplasmic reticulum and ribosome
What is the outcome of synapsis, a significant event in meiosis?
side-by-side alignment of homologous chromosomes
What is the term given to the theory that put forth the idea that living organisms could arise by incubating nonliving components?
spontaneous generation
Gregor Mendel's contribution to genetics is_____.
the discovery that traits are passed from parent to offspring in predictable ways
The phenotype of an organism is _______.
the observed features of an organism
Which of the following processes describes the formation of a complementary RNA molecule?
transcription
A ________ is an organism produced by biotechnology that involves the transfer of hereditary traits across species.
transgenic organism
The meiotic cell cycle involves ________ number of cell division(s) and ________ number of DNA replication(s).
two; one
What is the basis for homology among chromosomes?
type and location of genes
In a Chi-square analysis, what general condition causes one to reject (fail to accept) the null hypothesis?
usually when the probability value is less than 0.05
When does one use "reverse genetics"?
when the gene sequence is known, but the function is not, a scientist creates mutants to observe phenotypes and infer function
Can the deviation of observed values from expected values in cross (a) be attributed to random chance?
yes