HSS 2305 Chapter Notes - Chapter 11-12: Histone Code, Nucleosome, Epigenetics
18 Oct 2018
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Ch 11 & 12 gene-environment interaction and epigenetics. Chromatin: dna and associated proteins (histones, transcription proteins, etc. ) Histones: specialized proteins that associates with and packages dna: +ve change of histones interacts with ve charged backbone of dna, n-terminal segment can be modified by key enzymes having a profound effect on. Nucleosome: complex of histone proteins and supercoiled dna: 146bp of dna wrapped twice around histone core (histone octomer); 2x h2a, h2b, h3, h4. Dna packaging: h1 linker histone not in octomer, binds to linker dna and connects nucleosomes, histone packaging ratio of 10 000:1; condensed to loose = chromosome > chromatin. > heterochromatin (gene inactive b/c histones) > euchromatin (gene accessible) nucleosome > dna. Epigenetics study of heritable changes in gene expression or phenotype caused by mechs other than changes in underlying dna sequence. Incorporation of methyl groups can be influenced by environmental toxins i. e bpa.
