n marsupials, X inactivation occurs exclusively to paternally derived chromosomes. Which genes will
ALWAYS be expressed in this situation?
A. maternal X-linked genes
B. paternal X-linked genes
C. maternal Y-linked genes
D. paternal Y-linked genes
The correct answer is A. maternal X-linked genes.
In Marsupials, X inactivation occurs exclusively on the paternally derived chromosomes. This means that the X chromosome inherited from the mother, which carries maternal X-linked genes, will always be expressed. The X chromosome inherited from the father, which carries the paternal X-linked genes, will be subject to X inactivation and may or may not be expressed.