Chapter 12.4, Problem 3R

Summary Introduction

To review:

The reason due to which more number of males are affected by the red-green colorblindness as compared to females, with the help of a Punnett square.

Introduction:

Some of the traits in human genes are sex linked and therefore carried on sex chromosomes. These genes show a difference in their inheritance pattern from the genes located on the autosomes. One of the examples of sex-linked genes in humans is color blindness. The gene for red-green color blindness is carried on the X-chromosome, which results in the partial inheritance pattern in male and female, with males being more affected as compared to the females.

The sex-linked inheritance can be recessive or dominant. A sex-linked dominant inheritance would result in all the offsprings affected if only a single copy of that gene is inherited. A recessive form of the allele causes the defect in the progeny only when the progeny inherits the defective copy in homozygous condition.