Multiple Choice
A female with a deletion of the X-inactivation center (XIC) region on one of her X chromosomes will display which of the following phenotypes?
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3. Extensions to Mendelian Inheritance
X-Inactivation
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What is the result of the activation of the Xist gene in mammals?
A
Suppression of Y chromosome gene expression
B
Duplication of the X chromosome in all somatic cells
C
Coating and inactivation of one X chromosome in female cells
D
Activation of all genes on the X chromosome
Verified step by step guidance1
Understand that the Xist gene plays a crucial role in X chromosome inactivation, a process that occurs in female mammals to balance gene dosage between males (XY) and females (XX).
Recognize that activation of the Xist gene leads to the production of an RNA molecule that coats one of the two X chromosomes in female cells.
This coating by Xist RNA triggers a series of epigenetic modifications that silence gene expression on that X chromosome, effectively inactivating it.
Note that this inactivation is random in each cell and results in dosage compensation, ensuring that females do not have double the expression of X-linked genes compared to males.
Conclude that the activation of the Xist gene results in the coating and inactivation of one X chromosome in female cells, rather than affecting the Y chromosome or duplicating the X chromosome.
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