Fruit flies normally have dull red eyes, but geneticists have identified quite a few genes which cause them to have different colored eyes.

Fruit flies normally have dull red eyes, but geneticists have identified quite a few genes which cause them to have different colored eyes. The very first of these discovered was a gene with a recessive allele for white eyes. This gene isXlinked.Xlinkage works the same in fruit flies as it does in mammals. We'll use the symbolsW(dominant red eyes) andw(recessive white eyes) for these two alleles.

1. You mate a red eyed female fly (whose male parent had white eyes) to a male with red eyes. What are the genotypes of these two flies? Enter them on your answer sheet.
2. Fruit flies have hundreds of offspring at a time. When you look at the offspring from this mating, what phenotypic ratio do you expect to find? Don't forget that you are looking at the effects of anXlinked gene, and don't forget toinclude your workin the space provided. Your ratio must, of course, be properly expressed.