Multiple Choice
Which of these sequences plays a critical role in Barr body formation?
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3. Extensions to Mendelian Inheritance
X-Inactivation
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Join thousands of students who trust us to help them ace their exams!Watch the first videoMultiple Choice
Which of the following statements best applies to the inactive X chromosome in mammalian females?
A
It is always the paternal X chromosome that becomes inactive.
B
It is completely degraded during early embryonic development.
C
It is largely transcriptionally silent due to extensive DNA methylation and histone modifications.
D
It is actively transcribed to compensate for the active X chromosome.
Verified step by step guidance1
Understand the concept of X chromosome inactivation (XCI) in mammalian females, which is a process to balance gene dosage between XX females and XY males.
Recall that XCI involves one of the two X chromosomes becoming largely inactive, forming what is called a Barr body, to prevent overexpression of X-linked genes.
Recognize that the inactivation is not always paternal; it can be either the maternal or paternal X chromosome depending on the species and developmental stage.
Know that the inactive X chromosome is not degraded but remains present in the nucleus as a condensed structure.
Focus on the molecular mechanisms of inactivation, which include extensive DNA methylation and histone modifications that lead to transcriptional silencing of most genes on the inactive X chromosome.
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