BIOL 1000 Lecture Notes - Lecture 16: Topoisomerase, Helicase, Okazaki Fragments
2 Oct 2016
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Eukaryotic dna packing - histones: dna wraps around a nucleosome (two molecules each of histones h2a, h2b, h3, h4) . Binding of histone h1 causes nucleosomes to package into a coiled structure (solenoid or 30nm chromatin fiber) Can be loosely packed (euchromatin) or tightly (heterochromatin)(solenoid) know configuration. Non-histone proteins: a protein that associates with dna, mostly negatively charged or neutral and come in a variety of sizes, play a role in the expression of certain genes. Chromatin: dna plus associated proteins (histone and nonhistone proteins) Genes active in rna transcription: heterochromatin. Folds and packs to form thick, rod like chromosomes during nuclear division. Increasing size, developmental complexity, and diversity of functioning of multicellular eukaryotic organisms require strict control of cell division. Ultimately results in a mature body composed of different subpopulations of cells. Cell cycle: a period of growth followed by nuclear division and cytokinesis. Chromosomes: nuclear units of genetic information that are divided and distributed by mitotic cell division.
