Solved by a verified expert:Biology 93 HW 3 (Lv 2/3) Name:
Answer the questions in complete sentences
when appropriate
Chapter 15
1)
A male fruit fly heterozygous
for the gray body color and normal wing shape loci is crossed to a female fruit
fly that is homozygous recessive for the same loci. The cross produced the
following offspring:
body color
wing shape
offspring
grey (WT)
normal (WT)
778
black (mut)
vestigial (mut)
785
black (mut)
normal (WT)
158
grey (WT)
vestigial (mut)
162
Total
1883
What is the
recombination frequency between the two loci?
2)
A locus for eye color is also
on the same chromosome as the loci for body color and wing shape as the
previous problem. How would you setup a mapping experiment that can help you to
determine the order of all three loci? (Hint:
This is a two-step process where you will need to first generate some triple
heterozygous flies, and then cross these triple heterozygotes to some _____
individuals to generate the offspring that can tell you the order of these
genes.)
3)
Based on the following
offspring, determine the order of three loci mapped.
body color
bristles
eye color
offspring
grey (WT)
normal (WT)
red (WT)
394
sable (mut)
normal (WT)
red (WT)
84
grey (WT)
singed (mut)
red (WT)
12
grey (WT)
normal (WT)
white (mut)
83
sable (mut)
singed (mut)
red (WT)
75
sable (mut)
normal (WT)
white (mut)
21
grey (WT)
singed (mut)
white (mut)
79
sable (mut)
singed (mut)
white (mut)
427
Total
1175
4)
Two genes of a flower, one
controlling blue (B) versus white (b) petals and other other controlling
round (R) or oval (r) stamens, are linked and are 10 map
units apart. You cross a homozygous blue-oval plant to a homozygous white-round
plant. The resulting F1 progeny are then crossed with homozygous
white-oval plants to produce 1,000 F2 progeny. How many F2
plants of each of the four phenotypes are expected?
5)
Crossing over is thought to be
evolutionarily advantageous because it continually shuffles genetic alleles
into new combinations during meiosis. The human Y-chromosome pairs up with the
X-chromosome during meiosis but cannot undergo crossing over with the
X-chromosome due to lack of true counterparts (homology). What the Y-chromosome
does have, is eight regions containing 78 duplicate genes. What benefit, if
any, might these 78 duplicated genes on the Y-chromosome offer in terms of . . .
a)
contributing to the embryonic
development of the male fetus?
b)
contributing to genetic
diversity and evolution?
Chapter 18
1)
What would happen to expression
of an eukaryotic gene if . . .
a)
histone tail acetylation were
to increase in the cell?
b)
a hormone-receptor complex
enters the nucleus?
c)
there is a decrease in
expression of an activator protein that controls this gene?
d)
there is an increase in
expression of a miRNA that matches perfectly to the mRNA of this gene?
2)
Despite having the exact same
genome, your muscle cells express a very different set of proteins compared to
your brain cells. Briefly discuss how multicellular eukaryotic organisms
achieve differential gene expression in specialized cells. Be sure to include
cell differentiation in your discussion.
3)
Explain why a mutation in a
maternal effect gene will affect all offspring, regardless of the actual
genotype of the individual progeny. In addition, in the context of Drosophila
embryo development, how would a mutation in the bicoid gene in the mother,
affect the development of her progenies?
4)
The diagram to the right shows five genes, including
their enhancers in the Drosophila
genome. Imagine that A, B, C, D, E, and F activator proteins exist and can bind
to the corresponding control elements in the enhancers of these five genes.
a)
If gene 2 is expressed at a
high level in nerve cells, which enhancer element(s) would be bound by
activator protein(s)?
b)
If genes 1, 2, and 4 code for
nerve-specific proteins, while genes 3 and 5 are eye-specific, which activator
proteins must be present in each cell type to ensure expression of the
appropriate genes?
c)
If overexpressed due to a
mutation, which activator protein(s) could lead to misregulation of genes in
eye cells but not in nerve cells?
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