BIOL 1090 Study Guide - Final Guide: Histone H1, Spindle Apparatus, Dna Replication
22 Nov 2015
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Colasanti lectures 9 to 12 (i. e. cytoskeleton and nucleus) Explain what is meant by polarity in terms of the cytoskeleton. Dna is wound around small "spools" called nucleosome core particles, each of which consists of 8 histone proteins in an octect. The resulting chromatin fiber can then fold and coil to become even shorter and thicker. Each subunit is a nucleotide comprised of: a phosphate group, a five carbon sugar, one of four cyclic nitrogenous bases. The four nucleotides of dna: adenine, thymine, guanine, and cytosine. First level of condensation : packaging dna as a negative super coil into nucleosomes. Second level of condensation: an additional folding or supercoiling of the 11 nm fibre to produce a 30 nm fibre. This is driven by nucleosomal interactions (histone h1 involved). Third level of condensation - attachment of the 30 nm fibre at many positions to a non histone protein scaffold. This completes the condensation and packaging of dna into full chromosomes.
