Multiple Choice
Which of the following statements about the Xist gene is true?
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3. Extensions to Mendelian Inheritance
X-Inactivation
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Which of the following best describes the function of the Xist gene in X chromosome inactivation?
A
It encodes a protein that directly degrades X-linked mRNAs.
B
It produces a non-coding RNA that coats the X chromosome, leading to its inactivation.
C
It removes methyl groups from DNA to reactivate the inactive X chromosome.
D
It activates genes on the X chromosome to increase their expression.
Verified step by step guidance1
Understand that the Xist gene is involved in the process of X chromosome inactivation, which is a mechanism to balance gene expression between males (XY) and females (XX).
Recall that Xist does not encode a protein; instead, it produces a long non-coding RNA molecule.
Recognize that this non-coding RNA coats the X chromosome from which it is transcribed, spreading along the chromosome.
Know that the coating by Xist RNA triggers chromatin modifications that lead to the silencing or inactivation of that X chromosome.
Conclude that the function of Xist is to produce a non-coding RNA that coats the X chromosome, leading to its inactivation, rather than encoding a protein or modifying DNA methylation directly.
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