Download Biology 22 Problem Set 1 Spring 2003

Biology 22
Problem Set 1
Spring 2011
Due Thursday, March 24th, 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. Fabry disease, a condition in which the lack of a lysosomal enzyme leads to
nerve and kidney damage, is inherited with the recessive allele f on the X
chromosome. The X-linked dominant allele F prevents the disease. Colon
cancer susceptibility is inherited with the autosomal recessive allele c. The
autosomal dominant allele C prevents colon cancer.
a. Maurice has colon cancer susceptibility but does not have Fabry disease. His
wife Marion has Fabry disease but is not susceptible to colon cancer.
Marion’s mother is susceptible to colon cancer. For Maurice and Marion, what
is the probability that their first child will be a daughter with colon cancer
susceptibility who does not have Fabry disease and their second child will be
a son with Fabry disease and colon cancer susceptibility and their third child
will be a daughter who has neither colon cancer susceptibility nor Fabry
disease?
b. Out of four children born to Maurice and Marion, what is the probability that at
least one will be a son with Fabry disease who is not susceptible to colon
cancer?
c. Jerome has Fabry disease but is not susceptible to colon cancer. His wife
Janice is susceptible to colon cancer but does not have Fabry disease.
Jerome’s mother is susceptible to colon cancer. Janice’s father has Fabry
disease. For Jerome and Janice, what is the probability that their first child
with be either a son who has neither colon cancer susceptibility nor Fabry
disease or a daughter who is susceptible to colon cancer but does not have
Fabry disease?
d. Out of five children born to Jerome and Janice, what is the probability that
three will be daughters with both colon cancer susceptibility and Fabry
disease?
2. A prototrophic Hfr strain of E. coli with the genotype trp+ pyrC+ purB- is
conjugated with an F- strain with the genotype trp- pyrC- purB+. The trp gene is
known to enter last. The following numbers of recombinants were isolated:
trp+ pyrC- purB44
trp+ pyrC+ purB+
0
+
+
trp
pyrC
purB
96
trp+ pyrC+ purB260
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
4
F
42
D
70
E
101
F
8
C
20
E
60
D
91
B
2
F
11
A
49
E
63
C
5
A
31
E
45
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 hemophilia and rickets and a tail was mated to a male
rabbit that did not have hemophilia or rickets but lacked a tail. The F1 females
were all wild type, that is, not having hemophilia or rickets but having a tail.
The F1 males had hemophilia, rickets, and tails. A cross of F1 females to F1
males produced the following offspring in the F2 generation:
a.
b.
c.
d.
Phenotype For
Number of
Hemophilia
Rickets
Tails
Males Females
Hemophilia
No rickets Tail-less
13
0
No hemophilia Rickets
Tail
17
81
Hemophilia
Rickets
Tail-less
2
0
No hemophilia No rickets Tail
3
165
Hemophilia
No rickets Tail
51
86
No hemophilia Rickets
Tail-less
59
0
Hemophilia
Rickets
Tail
179
168
No hemophilia No rickets Tail-less
176
0
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.
What are the genotypes of the F1 males and females? Write each
genotype to show which alleles are linked together on the same
chromosome.
Draw a genetic map showing the distances between theses genes.
Express the distances in map units.
What is the degree of interference?
5. Deafness and red-green colorblindness in humans are determined by
recessive alleles at X-chromosome loci that are 10 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 colorblind son with
deafness?
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 colorblind son with
deafness?
Color Vision
Normal Hearing
Colorblind
Normal Hearing
Color Vision
Deafness
Colorblind
Deafness
I
II
III
1
2
3
4
5
6
7