What is a Barr body, and where is it found in a cell?

Verified step by step guidance

1. Understand that a Barr body is a dense, inactivated X chromosome found in the nuclei of female mammalian cells.
2. Recall that females have two X chromosomes, but to balance gene expression with males (who have one X chromosome), one X chromosome is largely inactivated during early development.
3. Recognize that this inactivated X chromosome condenses into a compact structure called the Barr body, which is visible under a microscope as a dense spot in the nucleus.
4. Note that the Barr body is typically located at the periphery of the nucleus within the cell.
5. Summarize that the Barr body represents a mechanism of dosage compensation to equalize X-linked gene expression between males and females.

Key Concepts

Barr Body

A Barr body is an inactivated X chromosome found in the nuclei of female mammalian cells. It appears as a dense, compact structure and represents the silenced X chromosome to balance gene dosage between males and females.

X-Chromosome Inactivation

X-chromosome inactivation is a process in female mammals where one of the two X chromosomes is randomly silenced during early embryonic development. This ensures dosage compensation so that females, like males, have one functional copy of X-linked genes.

Cellular Localization of Barr Body

The Barr body is located in the nucleus of somatic cells, typically attached to the inner nuclear membrane. It is visible under a microscope as a dense spot and is absent in male cells, which have only one X chromosome.