Question

In human female, barr bodies are formed by

• A. Inactivation of mother's X chromosome
• B. Inactivation of father's X chromosome
• C. Inactivation of both mother's and father's X chromosomes
• D. Inactivation of either mother's or father's X chromosome

Answer 1

The correct option is D Inactivation of either mother's or father's X chromosome

The inactivated X-chromosome in the somatic cell of the female is referred to as Barr body which is present as tightly coiled and visible heterochromatin. Dosage compensation in human is accomplished by the inactivation of one of the X chromosomes in females. It occurs in 200 celled embryo wherein each cell independently select either maternal or paternal X chromosome for inactivation. Once the selection is done, all lineages of that cell make the same selection during cell division and tissue differentiation. This random inactivation of maternal and paternal X chromosome makes a human female mosaic for X gene.

So, the correct answer is option D.