Question

X-linked Inheritance:

One gene relating to color vision is located on the X chromosom. Two alleles exist: the dominant allele (R) results in normal color vision, and the recessive allele (r) causes red-green colorblindness, in which the individual has difficulty seeing shades of red and green.
A man with Red-green colorblindness marries a woman who is neither colorblind, nor a carrier (heterozygous) for this form of colorblindness.
List your answers to the following questions below:
1) Using X and Y to denote sex - as is done in the last slide of the Mendelian Genetics slides in the Week 4/Lab module - indicate the man and woman's genotypes.
And using Punnett Squares, find the answers to the following questions (you will not be submitting this work, just using it to answer the questions):
2) What percentage of the couple’s children is likely to be Red-green Colorblind?
3) Will any of their children be carriers for the colorblindness trait?

Answer 1

Considering X-linked inheritance patterns, the couple's children cannot be red-green colorblind or carriers since the mother does not carry the recessive allele responsible for this condition. Their sons will inherit a normal X chromosome from their mother and a Y from their father, while daughters will inherit a normal X chromosome from each parent.

Step-by-step explanation:

Understanding X-Linked Inheritance and Red-Green Color Blindness

When discussing X-linked inheritance, a notable example is red-green colorblindness. The genotype of a male with red-green colorblindness would be XrY, and a female with normal color vision, who is not a carrier, would have the genotype XX. Now let's answer the questions based on Punnett Squares and X-linked inheritance:

The genotype of the man is XrY, and the woman's genotype is XX.

The percentage of the couple’s children likely to be Red-green Colorblind is 0%.

No, their children will not be carriers of the colorblindness trait since the mother does not possess the allele.

Why is there a 0% chance for their children to be colorblind or carriers? Colorblindness is an X-linked recessive condition and appears in males when they inherit the recessive allele from their mother. Since the female in this scenario does not carry the recessive allele, she cannot pass on colorblindness to her children.