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At the onset of X chromosome inactivation, the Xist and Tsix genes are coexpress

ID: 49299 • Letter: A

Question

At the onset of X chromosome inactivation,

the Xist and Tsix genes are coexpressed on only the future active X chromosome.

the Xist and Tsix genes are coexpressed on both X chromosomes.

the Xist and Tsix genes are coexpressed on only the future inactive X chromosome.

the Xist gene is expressed on only the future active X chromosome, while the Tsix gene is expressed on only the future inactive X chromosome.

the Tsix gene is expressed on only the future active X chromosome, while the Xist gene is expressed on only the future inactive X chromosome.

Explanation / Answer

the Tsix gene is expressed on only the future active X chromosome, while the Xist gene is expressed on only the future inactive X chromosome.\

the XIST allele must be turned off on one X chromosome to maintain its activity in cells of both sexes.