Genetics L311 Exam 2 s1

name:______student ID:______Genetics L311 exam 2 October 14, 2016

Directions: Please read each question carefully. Answer questions as concisely as possible. Excessively long answers, particularly if they include any inaccuracies, may result in deduction of points. You may use the back of the pages as work sheets, but please write your answer in the space allotted. However, you must show all your work. Clearly define your genetic symbols. We will not make guesses as to what a particular symbol is intended to mean. Also, don’t assume that strains are true-breeding unless this is stated in the question. Finally, show all your work. Good luck.

______(20 points possible)

(12 points possible)

total ______(of 100 points possible)

1. Short answers (2 points each, 20 points total) 1 name:______student ID:______A. A mutation in which the gene acquires some new activity is called a mutation.

B. An enzyme that can directly reverse pyrimidine dimers in the DNA, using visible light as a cofactor, is called .

C. is when the phenotype expected from one locus is dependent on the genotype of a second locus.

D. A mutation that completely eliminates gene function is called a(n) mutation.

E. The tendency of two or more genes located on the same chromosome to segregate together is called .

F. uses homologous DNA to repair DNA damage.

G. refers to the tendency of some disorders, such as Huntingon’s Chorea and Fragile X syndrome, to become more severe and with earlier age of onset in subsequent generations.

For the following, please provide a brief definition of the term given: H. silent mutation:

I. telomeres:

J. position effect variegation:

2. In the unusual Southeastern Indiana leafhopper, A. schlenzae, the genes an, hp, and pl are all linked. Mutation in an produces long antennae, in hp produces animals that can hop further (big hops), and in

2 name:______student ID:______pl produces pale rather than bright green color. Leafhoppers heterozygous for these three loci were crossed to the triple homozygous recessive and the following progeny were obtained. hp pl an 661 hp + an 3,547 + pl an 751 + + an 26 hp pl + 30 hp + + 730 + pl + 3,552 + + + 703 10,000 A. What is the order of the genes (2 points)?

B. What is the map distance between the three linked genes (6 points)? an – hp:

pl – an:

hp – pl: C. Assume for the rest of the problem (warning this does not necessarily represent the correct answer for a and b) that the order and distance are the following:

an 30mu pl 20mu hp

What is the probability of obtaining a phenotypic an pl + offspring from a cross between a heterozygous fly(an pl hp/+ + +) and a an pl hp recessive fly (4 points)?

3. Two recessive mutations have been identified in the Southern Michigan house fly, A. farlowae. p causes pink wings and s causes singed bristles. Recombination mapping is performed by crossing p s / ++ females with p s / p s males. Four distinct classes of progeny are produced. 412 pink wings, singed bristles 70 pink wings 82 singed bristles 436 wild type 1000 A. What is the map distance between the p and s genes (6 points)?

B. In another experiment, a male heterozygous for both mutations in cis is crossed with a female heterozygous for both mutations in trans. What fraction of offspring will be genotypically homozygous wild type for both genes (6 points)?

3 name:______student ID:______4. You find a rare cicada, B. kochae, in a remote location in Northern Kentucky. This species normally produces purple eyes but when a certain enzyme is not present the eyes are red. You cross the following true breeding strains together and get these results: Cross 1: Purple eyed male X red eyed female  all red eyes

Cross 2: Purple eyed female X red eyed male  all purple eyes

Cross 3: red eyed males from cross 1 X purple eyed females from cross 2  1/2 purple and 1/2 red

A. What mode of inheritance explains these results (4 points)?

B. If a cicada inherited a nonsense mutation that knocked out gene function in the paternal copy of the gene and inherited wild type from mom, what phenotype would the offspring show (4 points)?

C. If a cicada inherited a nonsense mutation that knocked out gene function in the maternal copy of the gene and inherited wild type from dad, what phenotype would the offspring show (4 points)?

5. You are attempting to determine if two genes, uni (which causes the Western Ohio rhinoceros beetle to grow a single horn) and big (which is responsible for enlarged wings) are linked. You cross a heterozygote with homozygous recessive to get the following results.

438 big winged, single horned 401 big winged 385 single horned 428 wild type

A. Please state the null hypothesis that you will test (2 points).

B. Please calculate chi square. Using the table at the right, what is the probability that your null hypothesis is incorrect? What can you conclude (8 points)?

4 name:______student ID:______6. You discover two unusual true-breeding strains of the iridescent tropical squirrel, S. ydeae. Both have pale blue fur. A cross of true-breeding strain 1 X true-breeding strain 2 produces all dark blue offspring. A cross of dark blue F1 X dark blue F1 produces the following:

453 dark blue 301 pale blue 49 white

A. Please give the genotypes of the F2’s on the lines provided above (8 points).

B. What is the probability that if you choose a pale blue-furred squirrel at random, it would be homozygous for all of the genes (4 points)?

7. In the deep water droll bluefish, most of the fish have dull scales whereas a recessive mutation produces shiny scales, and most have blue scales whereas a recessive mutation produces gray. One unusual droll bluefish is mostly wild type (i.e. dull scaled and blue) but has a small patch with shiny scales near a small patch with gray scales. Please diagram and name the process that produced this. (10 points).

8. The giant west coast banana slug grows 5 – 6 inches long and is normally found in shades of yellow or brown. Suppose you have identified the gene that controls pigmentation in banana slugs. The wild- type sequence includes the sequence: ATG TCT TAT TGT ATT GGG GTG 5 name:______student ID:______Met Ser Tyr Cys Ile Gly Val You sequence the gene from several strains and find the results given below. In each case please name the type of mutation, give the sequence of the resulting protein and give an example of a mutagen that is likely to produce the change listed. Because these animals live in damp, shady areas of the forest floor they are never exposed to UV light. An asterisk indicates the approximate location of the mutation. Do not use the same mutagen more than once (4 points each).

A. ATG TCT TAT TGT ATT AGG GTG Protein: Name of mutation: Mutagen:

B. ATG TCT TAT TGA ATT GGG GTG Protein: Name of mutation: Mutagen:

C. ATG CTT ATT GTA TTG GGG TG Protein: Name of mutation: Mutagen: