Download Biology 22 Problem Set 1 Spring 2003

Biology 22
Problem Set 1
Fall 2011 Due October 4th, 9:30 am
Hand in the solutions to each of the following problems. Put a box around each of
your answers and show your work for partial credit. You may consult your book,
lecture notes, other students and/or your instructor for assistance.
1. Familial Atypical Mycobacteriosis (FAM), in which individuals are susceptible
to infections by non-tuberculosis causing mycobacteria, is inherited with the
recessive allele f on the X chromosome. The X-linked dominant allele F
prevents Familial Atypical Mycobacteriosis. Colon cancer susceptibility is
inherited with the autosomal recessive allele c. The autosomal dominant
allele C prevents colon cancer.
a. Bruce has FAM but is not susceptible to colon cancer. His wife Bonnie does
not have FAM but does have colon cancer susceptibility. Bruce’s mother is
susceptible to colon cancer. Bonnie’s father has FAM. Out of 5 children born
to Bruce and Bonnie, what is the probability that at least one will be a son with
FAM and colon cancer susceptibility?
b. For Bruce and Bonnie, what is the probability that their first child will be a
daughter without FAM who is susceptible to colon cancer and their second
child will be a daughter with FAM who is not susceptible to colon cancer and
their third child will be a son who has neither condition?
c. Oscar has neither FAM nor colon cancer susceptibility. His wife Ophelia has
FAM but does not have colon cancer susceptibility. Oscar’s father and
Ophelia’s mother have colon cancer susceptibility. For Oscar and Ophelia,
what is the probability that their first child will be either a son with FAM and
colon cancer susceptibility or a daughter who has neither condition?
d. Out of 4 children born to Oscar and Ophelia, what is the probability that 3 will
be sons with FAM who do not have colon cancer susceptibility?
2. A prototrophic Hfr strain of E. coli with the genotype trp+ purB- pyrC+ is
conjugated with an F- strain with the genotype trp- purB+ pyrC-. The trp gene is
known to enter last. The following numbers of recombinants were isolated:
trp+ purB- pyrC0
trp+ purB+ pyrC+
24
trp+ purB+ pyrC56
trp+ purB- pyrC+
320
Draw a genetic map that shows the order in which these genes are arranged
and the distances between them.
3. Four different Hfr strains of E. coli transfer their genes in the order given
below:
Strain 1
Strain 2
Strain 3
Strain 4
Gene Markers
Entry Time
(min)
Gene Markers
Entry Time
(min)
Gene Markers
Entry Time
(min)
Gene Markers
Entry Time
(min)
A
8
F
42
B
90
E
108
F
5
D
31
E
52
B
70
C
2
F
13
A
47
B
78
D
4
A
12
C
80
Using these results, construct a linkage map of the circular E. coli
chromosome. Express the gene distances in transfer time (minutes) between
adjacent pairs of genes.
4. A female rabbit with rickets and hemophilia and a tail was mated to a male
rabbit that did not have rickets or hemophilia but lacked a tail. The F1 females
were all wild type, that is, not having rickets or hemophilia but having a tail.
The F1 males had rickets, hemophilia and tails. A cross of F1 females to F1
males produced the following offspring in the F2 generation:
Rickets
No rickets
Rickets
Rickets
No rickets
No rickets
Rickets
Rickets
No rickets
Phenotype
Hemophilia
Hemophilia
No hemophilia
Hemophilia
No hemophilia
Hemophilia
No hemophilia
Hemophilia
No hemophilia
Tails
Tail-less
Tail
Tail-less
Tail
Tail
Tail-less
Tail
Tail-less
Number of
Males Females
43
0
54
93
16
0
21
159
5
97
3
0
176
151
182
0
a. What are the genotypes of the original parents in this cross? Write each
genotype to show which alleles are linked together on the same
chromosome.
b. What are the genotypes of the F1 males and females? Write each
genotype to show which alleles are linked together on the same
chromosome.
c. Draw a genetic map showing the distances between theses genes.
Express the distances in map units.
d. What is the degree of interference?
5. In humans, deafness and blindness (due to the disease retinitis pigmentosum)
are determined by recessive alleles at X-chromosome loci that are 12 map
units apart. Consider the pedigree shown below.
a. What are the possible genotypes for individual III-3? What is the
probability for each possible genotype?
b. What is the probability that individual III-3 can have a son who is both
blind and deaf?
c. What are the possible genotypes for individual III-5? What is the
probability for each possible genotype?
d. What is the probability that individual III-5 can have a son who is both
blind and deaf?
Normal Vision
Normal Hearing
Blindness
Normal Hearing
Normal Vision
Deafness
Blindness
Deafness
I
II
III
1
2
3
4
5
6
7