Biology 93 HW – A male fruit fly heterozygous for the gray body color and normal wing shape

14 Jun Biology 93 HW – A male fruit fly heterozygous for the gray body color and normal wing shape

Question
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?