In fruit flies Drosophila one eye color gene is Xlinked with

In fruit flies (Drosophila), one eye color gene is X-linked, with a recessive white allele and a dominant red allele. If white-eyed female flies are bred to red-eyed male flies, describe the expected offspring (assume all parental flies are true-breeding). What results do you expect if you do the reciprocal cross (reverse the phenotypes of the parent flies)?

Solution

Answer:

Red(R)

white(r)

white-eyed female flies: XrXr

bred to red-eyed male flies: XRY

P1: XrXr x XRY

F1: XrXR (red female), XrY (white male)

Each 1:1 ratio

reciprocal cross

white-eyed male flies: XrY

bred to red-eyed female flies: XRXR

P1: XrY x XRXR

F1: XrXR (red female), XRY (red male)

Each 1:1 ratio