Question

The Salk Institute is trying to identify the genes related to eye color in fruit flies, but the samples were mixed up. They extracted DNA from a fly with the white eye mutation to compare the mixed up samples. After they extracted the DNA, they performed gel electrophoresis to compare the DNA patterns.

Claim: The unknown sample that has the white eye mutation is _____________.
Evidence: (How do you know?)
Reasoning: (What is the significance of your evidence?)
a) Heterozygous for the white eye mutation, as it shows a combination of both patterns.
b) Homozygous for the white eye mutation, as it matches the DNA pattern of the known white-eyed fly.
c) Not related to eye color, as the DNA pattern is different from the known white-eyed fly.
d) Unable to determine without more information.

Answer 1

The unknown sample that matches the known white-eyed fly's DNA pattern is most likely homozygous for the white-eye mutation, indicating a genotype with two recessive alleles for this X-linked trait in fruit flies.

Step-by-step explanation:

The unknown sample that has the white eye mutation is b) Homozygous for the white eye mutation, as it matches the DNA pattern of the known white-eyed fly. DNA gel electrophoresis allows for the comparison of DNA patterns, and if the pattern of the unknown sample is identical to that of the known white-eyed fly, it suggests that the alleles for eye color are the same in both. Since the white eye mutation is recessive and the flies are Drosophila melanogaster, where eye color is an X-linked trait, the match indicates that the unknown sample likely has two copies of the recessive allele indicating homozygosity for the trait.