What does X inactivation do in females?

Question

Natalie Ahrens · Accepted Answer

X inactivation is a process by which one of the copies of the X chromosome present in the female mammals is inactivated.

The X chromosome that has been rendered inactive condenses into a small structure known as the Barr body. Females carry two copies of the X chromosome, resulting in a double dose of X linked genes; to correct this imbalance, mammalian females have evolved the unique mechanism of X chromosome inactivation. In contrast to the gene-poor Y chromosome, the X chromosome contains over 1000 genes that are essential for proper development and cell viability. Barr bodies that are transcriptionally silent preserve gene equality between males (XY) and females (XX).

Isabella Anderson · Answer

undefined X inactivation, also known as lyonization, is a process in which one of the two X chromosomes in female cells becomes transcriptionally inactive. This ensures dosage compensation between males and females, as males have only one X chromosome while females have two. X inactivation occurs early in embryonic development and results in the formation of Barr bodies, which are condensed, transcriptionally inactive X chromosomes. As a result, each cell in a female's body expresses genes from only one of the two X chromosomes, effectively balancing gene expression between males and females.