What happens to the inactivated X chromosome in female mammals when cells divide?

• A. It is reactivated in every second generation of cells.
• B. It remains inactive and is passed on to daughter cells.
• C. It is completely degraded during cell division.
• D. It becomes active again in daughter cells.

Answer: (B)

Verified step by step guidance

1. Understand the concept of X-chromosome inactivation: In female mammals, one of the two X chromosomes is randomly inactivated during early embryonic development to ensure dosage compensation between males and females.
2. Recognize that the inactivated X chromosome forms a structure known as a Barr body, which is a dense, compact structure that remains in the nucleus.
3. During cell division, specifically during mitosis, the inactivated X chromosome (Barr body) is replicated along with the rest of the cell's DNA.
4. The inactivated state of the X chromosome is maintained through cell divisions. This means that the inactivation marks are preserved and passed on to daughter cells.
5. Conclude that the inactivated X chromosome remains inactive in daughter cells, ensuring that the same X chromosome remains inactivated in all subsequent cell generations.