name:_______________________
student ID:_____________________
Genetics L311 exam 2
October 24, 2014
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
_______
(23 points possible)
page 4
_______
(24 points possible)
page 5
_______
(24 points possible)
page 6
total
( 9 points possible)
_______ (of 100 points possible)
1
name:_______________________
student ID:_____________________
1. Short answers (2 points each, 20 points total)
A.
refers to a position on a chromosome, of a gene for
example.
B. Traits that appear in both genders but that are more severe in one gender than the other are
said to be
.
C. The tendency of two genes located on the same chromosome to co-segregate is
called
.
D.
are compounds that can be incorporated into the DNA
during replication and can cause mis-pairing, thereby inducing mutation (looking for the class
of compounds not a specific example).
E.
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.
F.
eukaryotic chromosomes.
are specialized structures found at the ends of many
G.
is the belief that traits influenced by the environment can
be passed on to subsequent generations.
For the following, please provide a brief definition of the term given:
H. Prion:
I. Photolyase:
J. Position effect variegation
2
name:_______________________
student ID:_____________________
2. In a fly the genes px, sp, and cn are all linked. Flies heterozygous for these three loci were crossed to
the total recessive condition and the following progeny were obtained.
px sp cn
px sp +
px + cn
px + +
+ sp cn
+ sp +
+ + cn
+++
1,461
3,497
1
11
9
0
3,482
1,539
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)?
px – sp:
sp – cn:
px – cn:
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:
px 30mu sp 20mu cn
What is the probability of obtaining a phenotypic px sp + offspring from a cross between a
heterozygous fly(px sp cn/+ + +) and a px sp cn recessive fly (3 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 (12 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?
3
name:_______________________
student ID:_____________________
4. When traveling in a cave near Bloomington, you came across a species of bat, T. nicholasae. Two
recessive mutations are known, one causing glow-in-the-dark wings (g) and the other causing hairy
feet (h). When trying to create a monster bat for a reality TV show, you cross heterozygous parents,
both with the mutations in trans, hoping to produce bats with hairy feet and glowing wings. Since the
mutations are only 4 mu apart you assume no double crossovers.
A. What are the genotypes of the parents (4 points)?
B. What percentage of offspring will have glowing wings and hairy feet (4 points)?
C. What percentage of offspring will have the same genotype as their parents (4 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)?
4
name:_______________________
student ID:_____________________
6. When on vacation, you discovered a species of giant spiders that were unusually colored. You found
two true-breeding strains, one green striped and one yellow striped. When you cross true breeding
yellow striped with true breeding green striped, you find that all the F1’s are green. When you perform
crosses amongst the F1’s, these are the following results:
481 yellow striped
358 blue striped
1082 green striped
A. What are the genotypes of the F2 progeny (8 points)?
B. What is the ratio observed (2 points)?
C. If you cross a blue F2 chosen at random with a homozygous recessive, what frequency of the
offspring will be yellow (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 next to one
another that differ from the rest of its skin. One has smooth scales with pink spots and the other has
jagged scales with yellow spots.
A. What are the genotypes of the parents and the offspring (6 points)?
Jagged scales, yellow spots:
Smooth scales, pink spots:
F1:
B. If these genes are linked, are they in cis or trans in the F1 offspring (2 points)?
C. Draw out the event that could have produced this individual. Please include the genes (8 points).
5
name:_______________________
student ID:_____________________
8. Using the following DNA sequence, consider each of the following cases separately. Use the chart
below to determine which of the amino acids corresponds to each codon.
First
Position
U
C
A
G
U
Phe
Phe
Leu
Leu
Leu
Leu
Leu
Leu
Ile
Ile
Ile
Met
Val
Val
Val
Val
Second Position
C
A
Ser
Tyr
Ser
Tyr
Ser
Stop
Ser
Stop
Pro
His
Pro
His
Pro
Gln
Pro
Gln
Thr
Asn
Thr
Asn
Thr
Lys
Thr
Lys
Ala
Asp
Ala
Asp
Ala
Glu
Ala
Glu
Third
Position
G
Cys
Cys
Stop
Trp
Arg
Arg
Arg
Arg
Ser
Ser
Arg
Arg
Gly
Gly
Gly
Gly
U
C
A
G
U
C
A
G
U
C
A
G
U
C
A
G
DNA Sequence
Resulting Protein
5’-ATGATAAGAGCATGA-3’
3’-TACTATTCTCGTACT-5’
(This is the original sequence.)
5’-ATGATAGGAGCATGA-3’
3’-TACTATCCTCGTACT-5’
don’t need to provide this
5’-ATGATAAAGCATGA-3’
3’-TACTATTTCGTACT-5’
5’-ATGCTAAGAGCATGA-3’
3’-TACGATTCTCGTACT-5’
6
Starting with the ATG on the top
strand, left hand side, please give the
sequence of the resulting protein.
Please name the type of mutation that
results from the change. Please name
a mutagen other than ionizing
radiation that is likely to produce the
mutation shown. You need not
provide the original protein sequence.
The arrow indicates the position of
the mutation. Please do not use the
same mutagen more than once (9 pts).
Type of
Mutation
not applicable
Possible
Mutagen
not applicable