Biol 300 Exam Questions

In Labrador retrievers Black coat (BB or Bb) is dominant to yellow (bb). A local breeder has recently had an increase in people wanting to reserve new yellow lab pups. He asks you to calculate the probability of getting a certain number of yellow labs in a cross of his male black lab and his female black lab. Importantly, each of the black labs he is mating had one yellow and one black parent. You might want to use pascal's triangle for this problem. However, an alternative to using the binomial expansion and Pascal's triangle in determining probabilities of phenotypes in subsequent generations when the parent's genotypes are known, is to use the following equation: What is the probability of having a litter consisting entirely of 5 yellow puppies (a litter of 5 puppies, all are yellow)?

0.00097656

What is the probability she passes all 3 recessive alleles on to her first child?

0.025

Considering just chromosome 7, what is the probability she passes on the dominant alleles for both T and Z to her first child?

0.05

What is the probability of a litter of 7 Labrador puppies consisting of exactly 4 yellow puppies and 3 black puppies.

0.05768

The recombination frequency between the R and T loci is .35. If a plant of genotype RT/rt is test-crossed to rt/rt, What proportion of the offspring will be Rrtt?

0.175

For a given cross, the expected number of double recombinants is 20 and the observed number of double recombinants is 15. What is the interference (I)?

0.25

The below genetic map shows three genes that are linked on a chromosome, and the distances between them. You perform a test cross of an individual of genotype ABC/abc and an individual with genotype abc/abc. There is no interference. What frequency of the offspring will be abc/abc?

0.352

What is the probability of having a litter of 5 with at least one yellow puppy?

0.7627

Calculate the Interference.

0.858

Use the pedigree below to answer the following question. In mice, black coat color is dominant to white coat color. In the pedigree below, mice with a black coat are represented by darkened symbols, and those with white coasts are shown as open symbols. What is the probability that I- 1, I- 2, AND II- 2 are all heterozygous?

1

Black fur in mice (B) is dominant to brown fur (b). Short tails (T) are dominant to long tails (t). What fraction of the progeny of the cross BbTt x BBtt will have black fur and long tails?

1/2

Josephine is planning to have children and visits a genetic counselor to predict the risk of passing on recessive alleles. Based on family history, she knows she is a carrier for alleles underlying 3 recessive conditions. The first, color blindness (she has Cc genotype), is X linked. The other two t syndrome and z syndrome are linked on chromosome 7 and separated by 10 cM. After having her genome sequenced, she knows that the T and z alleles are linked on one of her chromosome 7 homologs, while the t and Z alleles are linked on the other. Shown below are her homologous pairs of Chromosome 7 and the X chromosome. If her first child is a boy, what is the probability he will be color blind?

1/2

You conduct a monohybrid cross with Pure breeding round pea (RR) and pure breeding wrinkled pea (rr) parents. You then cross the F1s to make an F2 generation. What proportion of the F2 plants could be bred to produce offspring with a 3:1 phenotypic ratio?

1/2

If a plant is an autotetraploid with the genotype SSss, what proportion of the gametes it generates will be ss?

1/6

What is the probability that III 4 is carrier for BOTH condition A and B?

1/6

A woman with type A blood (whose father was type O) has children with a man that has type O blood. Both individuals (the woman and the man) are heterozygous for the MN antigen. Recall that MN blood group antigens are independent of the ABO locus, and that the M and N alleles are codominant. What is the probability of them having a girl that is type O with the M and N antigens?

1/8

The pedigree below illustrates the pattern of albinism (alleles A and a) inheritance in several human families. Filled in symbols represent the individuals with albinism. If II-3 and II-4 have a child, what is the probability it is a boy with albinism?

1/8

English bulldogs are prone to a recessive disorder called canine phosphofructokinase (PFK) deficiency, a condition in which glucose is unable to be metabolized into available energy. You are now considering breeding a female from litter f with the male from litter h. What is the probability that any given offspring will be affected with PFK deficiency? Note that f and g are two separate litters, but all of those 7 puppies are siblings.

1/9

In a diploid species of plant, allele T produces tall plants and is dominant to t for short plants, and allele O produces round fruit and is dominant to o for oval fruit. A tall dihybrid plant with round fruits (TtOo) is crossed with a short plant with oval fruit (ttoo). You know the genes are linked on the same chromosome, but you don't know the linkage arrangements of the alleles. The following progeny are obtained: The recombination frequency is

10%

In peppers, spicy is dominant to sweet and hairy stem is dominant to smooth stem. These traits are each controlled by a single gene, and the genes for the traits are located on separate chromosomes, meaning they sort independently. A spicy, hairy stemmed heterozygous pepper plant (SsHh) was crossed with a sweet, smooth stemmed plant (sshh) to generate offspring with the following phenotypes: Spicy and hairy-stem are dominant phenotypes, while sweet and smooth stem are recessive. Test these data for agreement with the expected phenotypic ratios of a test cross. What is the null hypothesis?

1:1:1:1

What phenotypic ratio would you expect as a result of a test cross between a dihybrid organism and one that is homozygous recessive at each of two independent loci?

1:1:1:1

What is the probability that II 5 is a carrier for condition A?

2/3

How many degrees of freedom?

3

What is the chi-square statistic?

3.125

In Labrador/golden retriever dogs (hybrid breed; goldador), short hair is dominant over long hair. Suppose a true-breeding, short haired lab is crossed with a long haired dog, and the F1 dogs are interbred (to produce F2s). The probability that the first puppy born in the F2 will have short hair is _______. If three puppies are born, the probability that all of them will have long hair is _______.

3/4; 1/64

If a eukaryotic chromosome was composed of 20% adenine, how much cytosine should theoretically be present in that same chromosome?

30%

The extraordinary accuracy of the DNA polymerase III enzyme lies in its ability to "proofread" newly synthesized DNA, a function of the enzyme's

3′-to-5′ exonuclease activity.

Based on the results in the above complementation table, how many genes are giving rise to the striped phenotype, and which strains have mutations in each of those genes (In other words which individuals are in the same complementation groups).

4 genes. Gene 1: a and b; Gene 2: c and f; Gene 3: e; Gene 4: d

Donkeys have a somatic chromosome number of 62. Hybrids produced by crossing donkeys and zebras are called zonkeys, are sterile, and have many characteristics intermediate between the two parental species. If a zonkey has 52 chromosomes, what is the somatic chromosome number of zebras?

42

Refer to the following fragment of an mRNA molecule shown below to answer the question. Translation begins at the AUG and proceeds from left to right: 5' AUGAAUAUA 3' Which option below correctly depicts the template strand of the DNA molecule from which this mRNA originated?

5' TAT ATT CAT 3'

Given the coding DNA sequence 5′-TAC AAA ATA CAG CGG-3′, which of these sequences represents a missense mutation?

5′-TAC AAA ATA CAC CGG-3′

In Drosophila, Z is dominant to z (zebra back), T is dominant to t (tie leg), and F is dominant to f (fuzzy wing). From a Drosophila testcross (trihybrid crossed with a homozygous recessive fly, ztf/ztf), the number of each phenotype obtained was as follows (individuals with a capital letter exhibit the dominant phenotype): Determine the order of the genes.

T -- Z -- F

Calculate the map distance genes in map units.

The distance between gene 1 and gene 2 (from you answer to Question 30) is 32 mU. The distance between gene 2 and gene 3 (from you answer to Question 30) is 22 mU.

Which of the following is true of the gametes of a human female who has nondisjunction of her X chromosomes in meiosis I?

The gametes contain 22 or 24 chromosomes.

The distinguishing feature of all next generation DNA sequencers that allows their extraordinarily high level of output is:

The technologies involve direct sequencing by synthesis of individual molecules

The diploid number of a species is 2n=30. Each diploid nucleus contains 5 ng of DNA in G1. What is the number of chromosomes and the amount of DNA contained in each nucleus at the end of the S phase?

There are 30 chromosomes containing 10 ng of DNA

Why are abnormalities in the number of sex chromosomes in mammals usually less severe in their phenotypic effects than abnormalities in the number of autosomes?

There are relatively few functional genes on the Y chromosome AND random X chromosome inactivation

In the test cross that produced the 4 phenotypes above, the genotype of the tall, round-fruited parent (the double heterozygote) is:

To/tO

What are the genotypes of the individuals crossed to obtain the progeny shown, reflecting linkage? This is a testcross. One parent is a triple homozygous recessive (tzf/tzf). The other parent is a triple heterozygote with linkage, but you don't know which alleles from each of the three genes occur on the same homologous chromosome.

TzF/tZf x tzf/tzf

Active transcription occurs in regions of chromatin loops that are located

a large distance away from the MARS.

What would you expect to find bound to the stop codon at the A site?

a translation release factor

Given a chromosome with the gene order, A B C D • E F G H, and an inverted chromosome with this gene order, A F E • D C B G H, which of the following recombinant chromosomes would result from a crossover between C and D?

A B C D • E F A and H G F E • D C B G H

A chromosome contains the following gene order: A B C D • E F G H Which of the following rearrangements represents a paracentric inversion?

A C B D • E F G H

What types of genetic approaches or analyses were used to (1) Identify and characterize COVID19 and (2) infer where and how it originated?

Next generation sequencing of an alveobronchial RNA sample, phylogenetic analyses of viral genomes

If nondisjunction occurs in meiosis II, what will be the result at the completion of meiosis?

One gamete will be n + 1, one will be n - 1, and two will be n.

You want to design a drug that prevents transcription of eukaryotic mRNAs but does not affect transcription of other RNAs. What enzyme would you target?

RNA Polymerase II

Which below best describes the viral genome structure of COVID19?

RNA coronavirus, genome size of 30,000 bases

Up to now, the predominant method of testing for COVID19 (as recommended by the CDC at least) has been:

Real time reverse transcriptase PCR

Below is an agarose gel showing the genotypes at a single gene in four offspring from a cross of two plants. The R allele is dominant and gives round seeds. The r allele is recessive and shorter due to a 50 bp deletion. You don't have access to the parents so don't know parental phenotypes or genotypes. What are (or could be) the phenotypes and genotypes of the parents?

Round (genotype: Rr), and wrinkled (genotype: rr)

The pedigree below illustrates the pattern of albinism (alleles A and a) inheritance in several human families. Filled in symbols represent the individuals with albinism. What is the mode of inheritance?

autosomal recessive

Which of these components would you use to distinguish whether a sample has been prepared for dideoxy sequencing reaction OR for polymerase chain reaction (in other words, which reagent is unique to one or the other)?

chain terminating ddNTPs

Which mode of inheritance results in both alleles being detected equally in the heterozygous phenotype?

codominance

Do you REJECT or FAIL TO REJECT the null hypothesis?

fail to reject

Which evolutionary process is most pronounced in small populations where statistical fluctuations in allele frequencies can be significant from one generation to the next?

genetic drift

When a hairless Mexican dog is mated to a dog with hair, about half of the puppies are hairless. When two Mexican hairless dogs are mated to each other, about 1/3 of the surviving puppies have hair and about 2/3 of the surviving puppies are hairless. Which of the following terms would create the best explanation of this pattern of inheritance: Mexican hairless dogs are __________ for a ________ allele that is lethal when __________.

heterozygous; dominant; homozygous

Which molecule would build up in a mutant strain that has both of the mutations in Met 1 and Met 4?

homoserine

If a trait is X-linked recessive, who would express the trait?

homozygous recessive females and hemizygous recessive males

The Shine-Dalgarno sequence in bacteria ________.

is a purine-rich consensus sequence found in the 5′ UTR of the mRNA

Which structure is responsible for chromosome movement during cell division?

kinetochore microtubules

Which type(s) of RNA is/are translated into proteins?

mRNA

Refer to the following fragment of an mRNA molecule shown below to answer the question. Translation begins at the AUG and proceeds from left to right: 5' AUGAAUAUA 3' What type of mutation is represented below? AUGAAGAUA

missense

You are investigating the inheritance of two rare conditions (A and B) in an extended family of Burnese mountain dogs. You have constructed the following pedigree for these conditions. A previous genetic analysis indicated that individuals I-1 and I-2 are both NOT carriers for condition A. What is the most likely mode of inheritance of each of these conditions (2 pts)?

condition A: autosomal recessive; condition B: X linked recessive

White eye color is an X-linked trait in one line of fruit flies. White eyes is recessive to red eyes. If a red-eyed female and a white-eyed male are crossed,

some of their male progeny could have white eyes

What is the approximate p-value?

somewhere between 0.30 and 0.50

Assume that you have a garden and some pea plants have solid leaves and others have striped leaves. You conduct a series of crosses [(a) through (e)] and obtain the results given below. What are the possible genotypes of the parents in cross (c)?

ss x ss

The P value is a quantitative expression of the probability that the results of another experiment of the same size and structure will deviate as much or more from expected results by chance. The greater the difference between observed and expected results of an experiment,

the greater the χ2 value and the lower the P value.

Syntenic genes can assort independently when:

they are very far apart on a chromosome and crossing over occurs frequently between them.

What dosage compensation mechanism is employed by female placental mammals?

x-inactivation

Below is an agarose gel showing the genotypes at a single gene in four offspring from a cross of two plants. The R allele is dominant and gives round seeds. The r allele is recessive and shorter due to a 50 bp deletion. You don't have access to the parents so don't know parental phenotypes or genotypes. Onto which end of the gel were the samples loaded, and did the smaller or larger fragments move the fastest?

A; smallest

Below is a list of 3 steps that will be repeated during a PCR reaction. Answer the following question about the missing information. Which of the following is correct regarding the missing information above (shown in double capital letters)?

AA should be 94, BB should be primer annealing

An animal heterozygous for a reciprocal balanced translocation has the following chromosomes (the dot refers to the centromere): What will the chromosome combinations be in the viable gametes?

AB • CDEFGH + mnlo • pqrs, and AB • CDEFrs + mnlo • pqGH

The syntenic genes A and Z are linked. A cross between two parents, AAZZ and aazz, produces F1 progeny with the AaZz genotype. What are the possible arrangements of alleles on the F1 progeny's chromosomes?

AZ/az

The pedigree below illustrates the pattern of albinism (alleles A and a) inheritance in several human families. Filled in symbols represent the individuals with albinism. The genotype of I-1 is __________.

Aa

The pedigree below illustrates the pattern of albinism (alleles A and a) inheritance in several human families. Filled in symbols represent the individuals with albinism. The genotype of II-4 is __________.

Aa

Which below most accurately describes how modern whole transcriptome sequencing works?

All mRNA is extracted, converted to cDNA, and sequenced on a next generation DNA sequencer

Dideoxy sequencing was performed using the DNA template strand: 3'- AGACGATAGCAT- 5' Which gel would result? The top of each gel below is the negative end, and is where the samples are loaded, the bottom is the positive end.

B

6 populations of Mimulus gutatus plants from different parts of the Sierra Nevada each have a low frequency of mutants that exhibit a striped flower phenotype. You want to know if this phenotype is controlled by one or multiple genes. You create 6 pure breeding lines of the mutant striped plants in your greenhouse at UNR. You cross the pure breeding mutant strains (a through f below), and obtain the below results of a complementation analysis, complementation is indicated with a plus. What best describes the genetic basis of the mutant phenotype? Mark all that are correct, or none.

Because multiple genes can influence the same phenotype, this is a result of epistasis It is controlled by an autosomal recessive allele

_________________ discovered the equal nucleotide ratios underlying base complementarity, and _________________ produced the first evidence that double stranded DNA exists in a double helix.

Chargaff; Franklin

In an allopolyploid organism, what is entirely true regarding the fertility of interspecies hybrids?

Chromosome doubling and nondisjunction in gametocytes can lead to homologous chromosome pairing, disjunction, and fertile hybrids.

Which of the following is FALSE regarding individuals who are heterozygous for a large inversion?

Crossovers between homologous chromosomes that occur outside the inverted region produce nonviable gametes.

You are working to determine the biochemical pathway for methionine synthesis in bacteria. The below mutant strains are auxotrophic (can't grow on minimal media). Which step is catalyzed by the enzyme mutated in Met 3?

Cysteine -> Cystathionine

What enzyme(s) is/are responsible for removal of RNA primers and joining of Okazaki fragments?

DNA polymerase I and DNA ligase

In the Hersey-Chase experiment, what did they determine was the genetic material and how did they radioactively label it?

DNA; P32 phosphorus

A tRNA in the P site of the ribosome will enter the ________ site after translocation of the ribosome.

E

A woman of genotype XAXa mates with a man of genotype XAY. They have a son with the abnormal genotype XAXaY. Did nondisjunction occur in the mother or in the father? Did it occur in meiosis I or in meiosis II?

Mother or Father, Meiosis I

What is one difference between DNA replication in bacteria versus eukaryotes?

Eukaryotic chromosomes have many origins of replication; bacteria have only one.

DNA and RNA synthesis proceeds:

From 5' to 3' direction

From the following tabulations of testcross progeny (a trihybrid parent, FfGgHh, crossed with a homozygous recessive parent, ffgghh) phenotypes and numbers, which below correctly illustrates the linkage relationships in the trihybrid parent?

GFh/gfH

Which histone protein is not part of the nucleosome structure?

H1

DNA helicase inhibitors are well studied as potential drug targets. What would you expect to see if DNA helicase activity is inhibited?

Helicase catalyzes ATP hydrolysis and DNA strands separation, so the helix cannot be unwound and strands will not separate.

A series of Arabadopsis mutants with deletions have been created. The locations of the deletions have been determined and are illustrated in the top panel below. These deletion mutants are crossed with a line that is homozygous recessive for each of the genes listed below. Use the information below to determine the order of these genes along the chromosome. + means offspring had wild type phenotypes, - means offspring had recessive phenotypes.

L E B R O N

Which of the following statements about DNA replication is NOT true?

Lagging strand is synthesized 5' to 3', while the leading strand is synthesized 3' to 5'

Refer to the following fragment of an mRNA molecule shown below to answer the question. Translation begins at the AUG and proceeds from left to right: 5' AUGAAUAUA 3' What is the amino acid sequence of the encoded polypeptide (use the genetic code below)? The correct answer should have the amino end on the left and the carboxy end on the right.

MET-ASN-ILE

Genetic linkage leads to the production of a significantly greater than expected number of gametes containing chromosomes with:

parental combinations of alleles

Which region(s) of a gene are not found within a eukaryotic mRNA transcript?

promoter region

You wish to create a mutation that prevents access of RNA polymerase to the gene. Which region of a gene would you mutate?

promoter sequence

Recombination is suppressed in individuals that are heterozygous carriers of chromosomal inversions because:

recombinant chromosomes are absent in the progeny.

Typically, acetylation of nucleosomes leads to:

relaxed packaging of the chromatin and increased transcription.