BIOL 112 Lecture Notes - Lecture 11: Enterobacteria Phage T4, Rna Virus, Dna Virus
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BIOL 112 Full Course Notes
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Nucleosome dna coiled around bundles of 8-9 histones proteins - beads on string. Mitosis nucleosomes undergo high-order packing = condensed chromosomes - inhibit transcription. A- nucleosome packing = methylation of histones *tighter packing = preventing transcription. *methylation also used in x-inactivation & on dna bases to repress gene activity. Histone methylation usually prevents transcription but sometimes can activate it. B- acetylation of histones = uncoiling & transcriptions proceeds. Interphase *no division chromatin exists as either of 2 types. Loosely bound to nucleosomes = genes actively being transcribed. 2- heterochromatin highly packed nucleosomes where dna inactive - genes cannot be transcribed. Condensed: darker contains lot of satellite dna = large tandem repeats of non- Transposons-jumping genes = dna segments that can move to new location on same/different. Chromosome *insertion of transposons into another region could cause mutation - little to no effect: transposon insertion sequences consist of only 1. Gene that codes for transposase enzyme to transports it.
