BIOL 3P50 Lecture Notes - Lecture 15: Polyadenylation, Histone H1, Tata Box
21 Sep 2017
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Document Summary
~ short region of dna double helix (2nm) ~ dna wrapped around histones; forms chromatin (11nm) ~ 2 dimers of 2a and 2b, 1 tetramer of h3 and h4 form nucleosome. ~ histone h1 binds to linker dna (15-55bp) ~ contains signal for 3" trim and polya tail addition. ~ gene is considered off when chromatin is condensed. ~ activator and mediator opens chromatin, turns gene on ~ a site wrapped tighter around the histone is harder to access. ~ certain proteins can access and target these sites. ~ transcription factors that the nucleosome can move or be removed. ~ some cres slide the nucleosome using atp. ~ certain dna sequences can favour or exclude nucleosome binding. ~ some are not conductive for nucleosome wrapping (i. e. <150bp) ~ protein positions nucleosome if dna forces nls away.
