BIOLOGY 2C03 Lecture Notes - Lecture 4: Chromosome, Ctcf, Meiosis
16 Oct 2015
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Document Summary
Epigenetics- a random, heritable (covalent modification of methylation or chromatin acetylation) of dna and dna- associated proteins) that affect gene expression without changing the nucleotide sequence. Changed in three ways: histone modification, nucleosome remodelling, dna methylation. Chromosomes have a core promoter region, a proximal promoter & down the chromo, enhancer and silencer sequences: all the above contain cis-acting regulatory sequences: regions regulate transcription of genes located on the same chromosome as them. Can control gene transcription of gene either close or far: ex. The extent of dna compaction changes transcribed into rna and by the. Double helix (cid:0) wraps around 8 histone (to keep it together) == octamer: beads on a string. 8 histones involved: 2 h3, 2 h4, 2h2a in a nucleosome during cell cycle, when genes are modifications proteins ~2x = nucleosome + h1 and 2h2b: 145-147 bp are wound. In the barr body, these proteins cannot bind. Initiated by rna polymerase and general transcription factors.
