X-Chromosome Inactivation Flashcards
1
Q
What is a Barr body?
A
An inactive X-chromosome in a cell with more than 1 X-chromosome. It is rendered inactive in a process called lyonization in species with XY sex-determination.
2
Q
What is the mechanism of X-inactivation?
A
Starts at the X-inactivation centre (Xic). Nuclei Xist colocalises with Barr body. Stabilisation of Xist RNA mediates initiation of X-inactivation. Xist expressed at very low levels in undifferentiated male/female embryonic stem cells. Becomes upregulated on one X chromosome upon differentiation of female cells.
