BIOC 2580 Study Guide - Final Guide: Ribosomal Rna, Tums, Transcription Factor Ii H
16 Dec 2015
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Document Summary
Loops of 50 turns per loop are formed. Minibands of 18 loops form resulting in stacked minibands called chromosomes. Eight histone fold protein domains for each nucleosome with nucleosomes connected by linker dna. Mediate atp-dependent (atpases) conformational changes in nucleosome structure. Repositioning (de-condensation usually) of nucleosomes to allow access to dna-binding sites (like the promoter region) Transcriptional activator protein can bind to recruit tfiid and the tata box binding protein to the tata box for rnap holoenzyme to join and transcribe. Introduce covalent modifications into the n terminal tails of the histone core octamer. Histones are usually positively charged and dna is negatively charged which is why they interact with such high affinity. By changing the charge on histones, the affinity of dna to histones can be changed. Acetylation of histone: dependent on acetyl-coa acetylation on lysine residues in histone tails by histone acetyltransferases the acetylation masks the positive charge of lysine to lower the affinity for dna.
