In fruit flies, eye color is a sex-linked trait. Red is dominant to white.

Question

What are the sexes and eye colors of flies with the following genotypes:

(4 points)
Male with red eyes Female with Red eyes Male with white eyes Female with white eyes








XRY
XrY
XrXr
XRXr

Answer 1

In fruit flies, eye color is determined by sex-linked genes, with the red eye color (R) being dominant over the white eye color (r). The alleles are located on the X chromosome, and males have one X and one Y chromosome (XY), while females have two X chromosomes (XX).

Let's analyze each genotype you provided:

1. Male with red eyes: XRY

   • Sex: Male (XY)
   • Eye color: Red (dominant trait)

2. Female with red eyes: XRXr

   • Sex: Female (XX)
   • Eye color: Red (has one dominant red allele)

3. Male with white eyes: XrY

   • Sex: Male (XY)
   • Eye color: White (homozygous recessive)

4. Female with white eyes: XrXr

   • Sex: Female (XX)
   • Eye color: White (homozygous recessive)

So the summaries are:

• Male with red eyes: Male, Red
• Female with red eyes: Female, Red
• Male with white eyes: Male, White
• Female with white eyes: Female, White