Question

Dr. Disney has been raising exotic fruit flies for decades. Recently, he discovered a strain of fruit flies that in the recessive condition have baby blue eyes that he designates as bb. He also has another strain of fruit flies that in the recessive condition have pink wings that are designated as pw. He is able to establish flies that are homozygous for both mutant traits. He mates these two strains with each other. Dr. Disney then takes phenotypically wild-type females from this cross and mates them with double recessive males. In the resulting testcross progeny he observes 500 flies that are of the following make-up: 41 with baby blue eyes and pink wings 207 with baby blue eyes only 210 with pink wings only 42 with wild-type phenotype What is the relationship with respect to location between the two genes?
a. They are linked and the map distance between them is 41.5 cM

b. They are linked and 16.6 cM apart

c. They are far apart on the same chromosome and assorting independently

d. They are on different chromosomes and assorting independently.

e. They are linked and 50.0 cM apart

Answer 1

Answer:

The correct option is (b). They are linked 16.6cM apart

Explanation:

Eye color is controlled by a sex linked gene. Baby blue eyes strain of fruit flies (recessive condition) = bb. Fruit fly strain with pink wings (pw, recessive condition) = pp. In fact, for studies of genes of unknown chromosomal location, the pattern is a diagnostic of location on the sex chromosomes