BIOL 2040 Lecture Notes - Lecture 16: Xist (Gene), X-Inactivation, Rna Interference
Document Summary
Process: xist, tsix: create rnai to block x chromosome covers chromosome. ensures the other homolog remains active. 3 types of inactivation: chemical modification of dna, attached histone proteins, or both. In typical 46, xx we need to cover only one x chromosome, just as with 47, xxy, however 46, Inactivation of x is not entirely effective, ~ 15% of genes are not silenced through the pathway. X chromosome in humans contains ~5% of all genomic dna! (150mbp) **pairing of homologs is required + mediated by xic region! inactivation of x is random occurs in somatic cells in early embryonic development. Somatic mosaic: random inactivation of x chromosomes leads to different gene expression in each cell (females). Males do not have somatic mosaic and are more prone to. If you have early vs. late inactivation of x, you will get different phenotypes. In slide with patches on someones body, large patches indicates early x inactivation.
