Chapter 7, Problem 16QP

Summary Introduction

To determine: The reason which makes calico cats almost invariably female.

Introduction: Females have two X chromosomes due to which they have two copies of all the genes present on that chromosome whereas males carry only one copy of X chromosome due to which they have only one copy of the gene present on that chromosome. All female mammals contain a genetically inactive X chromosome which is known as the Barr body. The expression of gene products by the genes present on the X chromosome is equalized in both males and the females.