name:______
student ID:______
Genetics L311 exam 2
March 4, 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.
page 2______(20 points possible)
page 3______(21 points possible)
page 4______(24 points possible)
page 5______(20 points possible)
page 6 (15 points possible)
total______(of 100 points possible)
1. Short answers (2 points each, 20 points total)
A.A class of chemicals that tends to insert between adjacent base pairs of DNA causing misalignment of the strands leading to loss or addition of an individual nucleotide is called a(n).
B. is the belief that traits influenced by the environment can be passed on to subsequent generations.
C.The tendency of two genes located on the same chromosome to co-segregate is called .
D.Based on the position of its centromere, this chromosome is said to be .
E.Traits that appear in both genders but that are more severe in one gender than the other are said to be .
F. refers to a position on a chromosome, of a gene for example.
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.Photolyase:
I.Holocentric:
J.Synonymous mutation:
2.In the rare waltzing cricket the genes b, c, and d are all linked. Mutation in b causes animals to be brown rather than red, mutation in ccauses altered chirps and mutation in d causes defective dancing. Crickets heterozygous for these three loci were crossed to the total recessive condition and the following progeny were obtained.
178Altered dance, altered chirps, brown
3197Altered dance, altered chirps
27Altered dance, brown
160Altered dance
166Altered chirps, brown
29Altered chirps
3211Brown
173Wild type
7141
A. What is the order of the genes (2 points)?
B. What is the map distance between the three linked genes (6 points)?
b - c:
c - d:
b – d:
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:
b 15 mu c 20mu d
What is the probability of obtaining a phenotypic +c + offspring from a cross between heterozygous crickets (b c d/+ + +) andb c d triple recessive cricket (5 points)?
3.A rare condition is controlled by a paternally imprinted gene. A man who is homozygous mutant for this gene marries a woman who is homozygous wild-type. All who marry in are wild type (8 points).
What is the probability that his sons will show the trait?
What is the probability that his daughters will show the trait?
What is the probability that his son’s son will show the trait?
What is the probability that his daughter’s son will show the trait?
4.Two recessive mutations have been identified in the rare Indiana six-toed salamander, E. qinae. r causes wrinkled skin and b causes bent tails. Recombination mapping is performed by crossing r b / ++ females with r b / r b males. Four distinct classes of progeny are produced.
431wrinkled skin, bent tails
37wrinkled skin
41bent tails
419wild type
928
A. What is the map distance between the r and b genes (4 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 (8 points)?
5.You are attempting to determine if two genes in zombie mole rats, pl, which causes pale skin and mn, which causes animals to moan eerily, are linked. You cross heterozygotes with homozygous recessive to get the following results.
118 pale, moaning
101 pale
103 moaning
120 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 (10 points)?
6. When on vacation, you discovered a species of giant spiders with different strains that were unusually colored. You found two true-breeding strains, both with pale blue stripes, on two different islands. When you cross the two strains, you find that all the F1’s have dark blue stripes. When you perform crosses amongst the F1’s, these are the following results:
422pale blue striped
628dark blue striped
70white striped
1120
A. What are the genotypes of the F2 progeny (8 points)?
B. If you cross a dark blue striped F2 chosen at random with all homozygous recessive, what frequency of the offspring will be white striped (4 points)?
7.You come across two true breeding strains of purple people eaters on an expedition through Antarctica. One strain has smooth scales and pink spots on its belly. The other strain has jagged scales and yellow spots on its belly. The traits are controlled by two different genes. You become attached to the purple people eaters and decide to study them more. You cross the two strains and get jagged scales and pink spots. Surprisingly, one of the offspring has two small patches, one with smooth scales with pink spots and the other with jagged scales with yellow spots, near one another. Please draw out clearly the event that could have produced this individual. Please include the genes (8 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
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 (3 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. Provide the name of the mutagen, a brief description of its mode of action in the table below and the type of mutation that results. See the first line for an example (9 points).
Name of compound / Mechanism of action / Type of mutation producedexample: ultraviolet light / causes pyrimidine dimers / frameshift (other answers possible)
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