MBG 2040 Study Guide - Final Guide: Proteome, Shelterin, Topoisomerase
Document Summary
Eukaryotic dna is supercoiled: aids in chromatin packaging. H1, h2a, h2b, h3, h4: conserved proteins, basic, arginine and lysine - abundant - interact with negatively charged phosphate groups in dna, structural role in chromatin. Stable dna structure is ideal for storing genetic information - adenine and thymine form two hydrogen bonds. Guanine and cytosine form three hydrogen bonds. Chemical analysis of isolated chromatin shows that it consists primarily of dna and proteins with lesser amounts of rna. The proteins are of two major classes: (1) basic (positively charged at neutral ph) proteins called histones, (2) a heterogeneous, largely acidic (negatively charged at neutral ph) group of proteins collectively referred to as nonhistone chromosomal proteins. Histones play a major structural role in chromatin. Four of the five types of histones are specifically complexed with dna to produce the basic structural subunits of chromatin, small ellipsoidal beads called nucleosomes. Prevent deoxyribonucleases from degrading the ends of the linear dna molecules,