You now know that inheritance of eye color in fruit flies is sex-linked: The gene encoding eye color is located on the X chromosome, and there is no corresponding gene on the Y chromosome. White is recessive to red. How would the inheritance pattern differ if the gene for eye color were instead located on an autosome (a non-sex chromosome)? Recall that for autosomes, both chromosomes of a homologous pair carry the same genes in the same locations. Suppose that a geneticist crossed a large number of white-eyed females with red-eyed males.
female x male
Consider two separate cases:
* Case 1: Eye color exhibits sex-linked inheritance.
* Case 2: Eye color exhibits autosomal (non-sex-linked) inheritance. (Note: In this case, assume that the red-eyed males are homozygous.)
For each case, predict how many of the male and female offspring would have red eyes and white eyes.
Case 1: Eye color exhibits sex-linked inheritance
1. If there were 100 female offspring, [ ] would have red eyes and [ ] would have white eyes.
2. If there were 100 male offspring, [ ] would have red eyes and [ ] would have white eyes.
Case 2: Eye color exhibits autosomal (non-sex-linked) inheritance
3. If there were 100 female offspring, [ ] would have red eyes and [ ] would have white eyes.
4. If there were 100 male offspring, [ ] would have red eyes and [ ] would have white eyes.