Drosophila Cross? (scarlet + brown = white eyes)

[Wouter Ferro]

James Ford wrote in message <7d3bl4$jok at freenet-news.carleton.ca>...
>Could anyone give me a simple explaination  why when scarlet + brown
>recessive alleles are homozygous in a fruit fly, that the fruit fly will
>then be white eyed.

eye color in Drosophila consists of 2 pigments. Scarlet and brown are in the
pathway of either pigment. Hence 1 knocked out gives brown or scarlet
pigment only; both knocked out no pigment = white.