BIOL 200 Lecture Notes - Lecture 11: Dna Replication, Okazaki Fragments, Ribonucleoprotein
23 Jan 2018
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Chromatin: condensation, 1:1 mass of protein to dna. Isotonic buffer vs low salt: low salt decondenses dna beads on a string . Protein core: condensed: 30 nm fiber (beads on the string made compact. Ends of histones can protrude outside protein tail (n-terminals and c-terminals) Moderates gene expression by controlling access to genes. By modification of tails: post-translational process, example: Acetylation of lysine to get rid of positive charge on amino group. Neutralized interaction with sugar-phosphate backbone of dna: decondensation of dna. Not all occur at the same time. Histone code : you can predict if it"s going to be open or more closed. Result of experiment: globin gene is decondensed and condensed and subjected to dnase (which degrades dna) Condensed: dnase can"t access it: mimics interaction of other enzymes ex: transcription factors, 30 nm loops. To get rid of histone subject to detergent.
