BIOL 200 Study Guide - Final Guide: Sister Chromatids, Dna Profiling, Messenger Rna
23 Nov 2012
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Document Summary
The 30nm fiber is the dna in its interphase state. The dna is wrapped around the histone complex and then is twisted into a solenoid structure, the 30 nm fiber. The histones are acetylated and deacetylated on lysine residues in the n- terminal tail and on the surface of the nucleosome core as part of gene regulation. Acetylation removes the positive charge on the histones, thereby decreasing the interaction of the n termini of histones with the negatively charged phosphate groups of dna. As a consequence, the condensed chromatin is transformed into a more relaxed structure that is associated with greater levels of gene transcription. Antisense dna is the non-coding strand complementary to the coding strand in double-stranded dna. The antisense strand serves as the template for messenger rna (mrna) synthesis. A centromere is a region on a chromosome that joins two sister chromatids.
