Which of the following statements about Barr bodies is true?
Barr bodies are present in both male and female cells
Barr bodies are essential for normal cell function
Barr bodies can be observed in live cells using a microscope
Barr bodies are formed by the inactivation of the Y chromosome
The correct answer is a) Barr bodies are present in both male and female cells. Barr bodies are only observed in female cells and represent the inactivated X chromosome. In male cells, which have a single X chromosome, a Barr body is not formed.
The Barr body is a compacted and inactivated X chromosome that appears as a dense spot in the nucleus of female cells. It is formed during early embryonic development as a result of random X chromosome inactivation, which is a process that equalizes gene expression between males and females. The inactivated X chromosome is then packaged into a Barr body, which is silenced and largely transcriptionally inactive. Barr bodies are not essential for normal cell function and are not visible in live cells using a microscope.
Option 1 is the correct answer.