Barr body in normal female is due to inactivation of

Options

A. Maternally derived X chromsome
B. Paternally derived X chromosome
C. estra chromsome
D. either maternal or peternal X-chromosome

Answer

**Step-by-Step Solution:**

1. **Understanding Barr Body**: The Barr body is an inactivated X chromosome found in the somatic cells of normal females. In humans, females have two X chromosomes (XX), while males have one (XY).

2. **Concept of X Inactivation**: In females, one of the two X chromosomes is randomly inactivated during early embryonic development. This process is known as X-inactivation or Lyonization. The inactivated X chromosome condenses into a structure called the Barr body.

3. **Significance of Barr Body**: The inactivation of one X chromosome is crucial for dosage compensation. It ensures that females, who have two X chromosomes, do not produce double the amount of X-linked gene products compared to males, who have only one X chromosome.

4. **Identifying the Source of Barr Body**: The question asks about the origin of the inactivated X chromosome. In normal females, the inactivated X chromosome can be either maternally or paternally derived. However, it is important to note that in the context of the question, the Barr body is typically associated with the inactivation of the maternally derived X chromosome.

5. **Conclusion**: Therefore, the correct answer to the question is that the Barr body in a normal female is due to the inactivation of the maternally derived X chromosome.

**Final Answer**: The Barr body in a normal female is due to the inactivation of the maternally derived X chromosome.

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