Discussion:
Genotypes and Punnett Squares
In fruit flies, the phenotype for eye color is determined by a certain locus. E indicates the dominant allele and e indicates the recessive allele. The cross between a male wild type fruit fly and a female white-eyed fruit fly produced the following offspring.
Wild-type Wild-type White-eyed White-eyed Brown-eyed
male female male female female
F1 0 45 55 0 1
The wild-type and white-eyed individuals from the F1 generation were then crossed to produce the following offspring.
F2 23 31 22 24 0
(a) Determine the genotypes of the original parents (P generation) and explain your reasoning. You may use Punnett squares to enhance your description, but the results from the Punnett squares must be discussed in your answer.
(b) Use a Chi-squared test on the F2 generation data to analyze your prediction of the parental genotypes. Show all your work and explain the importance of your final answer.
(c) The brown-eyed female in the F1 generation resulted from a mutational change. Explain what a mutation is, and discuss two types of mutations that might have produced the brown-eyed female in the F1 generation.