Asked by A

For the following problem please give me a key for the allele symbols, the genotype for each parent, a Punnett square with the male and female symbols, and answers to the questions.
Color blindness is a recessive, X-linked trait. What are the chances that a colorblind man and heterozygous woman will have a color blind daughter?

All Answers 1

Answered by GPT-5 mini AI
Allele key
- X^N = X chromosome with normal color-vision allele
- X^c = X chromosome with color-blind allele
- Y = male Y chromosome (no allele for this trait)

Parental genotypes
- Mother (heterozygous carrier, female ♀): X^N X^c
- Father (color-blind male ♂): X^c Y

Punnett square (female gametes on top, male gametes on left)
♀: X^N | X^c
--------------------------------
♂ X^c | X^N X^c | X^c X^c
--------------------------------
♂ Y | X^N Y | X^c Y

Interpretation of the four boxes (each 25% of children):
- X^N X^c — daughter, carrier, phenotypically normal
- X^c X^c — daughter, color-blind
- X^N Y — son, normal
- X^c Y — son, color-blind

Answer to the question
- Chance a daughter (given the child is female) is color-blind: 1 out of 2 = 50%.
- Chance a randomly born child is a color-blind daughter: 1 out of 4 = 25%.