Download Biology 22 Problem Set 1 Spring 2003

Biology 22 Problem Set 1 Winter 2011 Due January 19th at 10:30 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. Chronic Granulomatous Disease (CDG), an immune deficiency characterized
by a defect in phagocytosis, is inherited with the X-linked recessive allele g.
The X-linked dominant allele G prevents the disease. A straight hairline is
inherited with the autosomal recessive allele w. Individuals with the
autosomal dominant allele W have a widow’s peak, where the hairline comes
to a v-shape in the middle of the forehead.
a. Robert has a widow’s peak and CDG. His wife Renee has a straight hairline
and does not have CDG. Robert’s mother has a straight hairline. Renee’s
father has CDG. Out of five children born to Robert and Renee, what is the
probability that at least one will be a son with a widow’s peak who does not
have CDG?
b. For Robert and Renee, what is the probability that their first child will be either
a son with a straight hairline and CDG or a daughter with a widow’s peak and
CDG?
c. Preston has a straight hairline and does not have CDG. His wife Patricia has
CDG and a widow’s peak. Patricia’s mother has a straight hairline. For
Preston and Patricia, what is the probability that their first child will be a son
with a straight hairline and CDG and their second child will be a daughter with
a widow’s peak who does not have CDG and their third child will be a
daughter with a straight hairline who does not have CDG?
d. Out of 3 children born to Preston and Patricia, what is the probability that 2
will be sons with widow’s peaks and CDG?
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+
trp+
trp+
trp+
purBpurB+
purB+
purB-
pyrCpyrC+
pyrCpyrC+
0
108
48
244
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
3
C
32
B
51
D
84
C
5
E
26
D
44
B
77
F
2
C
17
A
46
D
56
E
6
A
14
D
24
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, 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.
Hemophilia
Rickets
Tails
Males Females
Hemophilia
No rickets Tail-less
2
0
No hemophilia Rickets
Tail
3
48
Hemophilia
Rickets
Tail-less
63
0
No hemophilia No rickets Tail
57
194
Hemophilia
No rickets Tail
40
52
No hemophilia Rickets
Tail-less
35
0
Hemophilia
Rickets
Tail
146
206
No hemophilia No rickets Tail-less
154
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 these genes. Express
the distances in map units.
What is the degree of interference?
5. In humans, deafness (d) and blindness (b, due to the disease retinitis
pigmentosum) are determined by recessive alleles at X-chromosome loci that
are 18 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