Bio 340_ Lecture 11%2F13%2F17.docx - How can DNA be...

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How can DNA be remodeled when it’s wrapped around a histone?Chromatin remodeling-Sliding nucleosomes along DNA-Removing nucleosomes/swapping histonesChromatin modification-Adding or removing acetyl. Methyl, or other groups-Alters DNA binding affinity to nucleosomesChromatin = the complex of DNA and proteins that together make up eukaryotic chromosomesChromatin modification (by chromatin modifiers) involves chemically modifying histone tails-- modifications involve covalent addition or removal of phosphate, methyl, or acetyl groups, orprotein tags called ubiquitinEXAMPLE: acetylation: adding an acetyl group-Reduces the positive charge, loosening the interaction with DNAEukaryotic gene regulation take home message:-Large eukaryotic genomes require several orders of compaction to fit into a nucleus; thisdepends on nucleosomes-Nucleosomes consist of positively charged histone proteins with DNA wrapped aroundalmost twice-Nucleosomes often prevent access to promoters, so they have to be remodeled by-- sliding nucleosomes along DNA-- removing nucleosomes/swapping subunits-Or modified-- adding or removing acetyl, methyl groups, etc-- alters DNA binding affinity to nucleosomesTRANSLATIONGene expression: the steps through which a gene influence phenotypeProteins are polymers composed of units called amino acids-Twenty amino acids are known to exist in proteins-They differ in the structure and chemical properties of their side groupsPolypeptides are chains of amino acids linked together by peptide bondsProtein structure has four levels of organization:

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Term
Spring
Professor
Pratt

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