In fruit flies, brown eyes can be caused by recessive mutant alleles of any one of three genes: pn (prune), bw (brown) or ry (rosy). The pn gene is X-linked, bw is on the second chromosome, and ry is on the third chromosome. One wild-type allele of each of the three genes must be present for eyes to be red (wild type). Suppose that two brown-eyed flies are crossed and their progeny consist of brown-eyed sons and red-eyed daughters. Which mutation is responsible for the brown eyes in the parental female?

Question

A) pn
B) bw
C) ry
D) either bw or ry
E) any of the three—pn, bw, or ry

Answer 1

A) pn