Correct answers in bold
- (5 points) The figure to the right shows a chromosome during mitotic metaphase. Which term best describes the structure of this chromosome? (Note: see bottom left panel of textbook Figure 5.5 for image)
a) metacentric
b) acrocentric
c) chiasma
d) compensatory
2. (5 points) The Y chromosome in humans is thought to have evolved from a homologous partner to which other chromosome?
a) Chromosome 21
b) Chromosome 22
c) The Z Chromosome
d) The X Chromosome
3. You are studying the rb gene (rb indicates recessive mutant allele, + indicates wild-type) and cv gene (cv indicates recessive mutant allele, + indicates wild-type) in Drosophila. Both genes are on the X chromosome. You set up a testcross between a doubly heterozygous female and a male tester fly. You infer the following genotypes from the phenotypes observed in the male progeny of this cross:
Genotype Number Observed
+ + / Y 90
+ cv / Y 11
rb + / Y 9
rb cv / Y 90
Part A (5 points): Does this data suggest that the rb and cv genes are linked?
a) Yes
b) No
c) Not Enough Information Provided
Part B (5 points): What is the genetic distance (in cM) between rb and cv?
(9+11)/200 = 20/200 = 0.10 recombination freq. (x100) = 10 cM
