Biology 1002B Lecture Notes - Lecture 15: Mutation, Chromatin, Nucleosome
15 Mar 2013
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Document Summary
Xist (x inactive specific transcript) rna binds along the inactive x chromosomes, silencing most genes. The genes become in inaccessible to transcription machinery by xist rna coating the chromosomes and making them inactive (stable throughout the life) Random x chromosome inactivation creates genetic mosaics in females. All of the decedents of the original cell, maintain the same x-chromosome inactivation (maternal/paternal) Xist and tsix are transcribed in apposite directions at same locus. Tsix shuts of xist (there are not pns here, just rna) What if we compare genomes and x inactivation in alice and beth. Alice is inactivating each half the time. Beth is inactivating only one of them all the time. Nucleosome: dna wound around core of 2 molecules each of h2a, h2b, h3, h4. Dna that is more open is more available for transcription. Nucleosomes can be moved, to remodel chromatin near promoter. Pack them tighter, move them around the make them more/less available for transcription (epigenetic regulation)
