BIOL 202 Lecture Notes - Lecture 28: Chromosome, Wild Type, Dna Replication
Document Summary
Chromatin structure: heterochromatin: no access of dan binding protein, euchromatin: coding and transcribed regions, cofactors, chromatin remodeling (change chromatin architecture) A 9-protein complex uses atp to move nucleosomes alone the chromosome (push to the sides), exposing regulatory sequences. Can have both positive and negative affect on transcription: post translational modifications (change histone tails histone code) Affect affinity of dna to binding proteins: hyperacetylation, by hats, neutralize histone tail charges, weaken association with dna, looser histone. Dna interaction: easier for proteins to bind, usually actives transcription, tf (activators) recruit co-activators (cbp, yeast gcn5) that are specific to hat activity, hypoacetylation. Recruits hdac and yeast rpd3: beta interferon enhancer. Sits between 2 nucleosomes, blocks tata box. In response to viral infection, gcn5 and cbp adds to the enhanceosome complex, acetylate nearby histone tails, makes nucleosome looser, promotes transcription: methylation. Usually seen in heterochromatin and gene silencing. Recruited by hp1 (heterochromatin protein1, which binds to already methylated histones)
