Lecture 10 - Chromatin

Lecture 10 - Chromatin - Chromatin DNA associated with...

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Chromatin DNA associated with histone proteins (H1-H4) in cell - bound strongly and wind up into nucleosome (high-order) - necessary for the packaging of DNA of this length into chromosomes modification of the chromatin results change in gene expression regional unwinding of chromatin facilitates expression of the contained genes - may be carried out by large complexes, histone modifying enzymes, chromatin remodelling complexes and components of RNAP II complex three genetic loci on S. cerevisiae control mating type (on chromosome III) - HMLalpha and HMRa need to be silenced otherwise cells are diploid, cannot mate - Repression based on silencer sequences, works outside of mating too and can repress tRNA expression o If analogous Ecoli gene introduced, it is methylated, except in the silencer regions - Experiments indicate histones affect repression, telomeric regions behave similarly RAP1 binds to DNA in silencer, also to telomeres SIR 2, 3, 4 bind to hypoacetylated histone tails (H3, H4) and form large
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This note was uploaded on 04/22/2008 for the course BIOL 200 taught by Professor Bureau during the Fall '06 term at McGill.

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Lecture 10 - Chromatin - Chromatin DNA associated with...

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