Biology 3593B Study Guide - Quiz Guide: Nucleoid, Dna Supercoil, Deoxyribonuclease
Document Summary
Membrane free: likes it rough: (mf: 60% dna, 30% rna (mrna, trna, rrna, 10% protein, mainly rna pol. Membrane associated: (ma) gentler maintain more structure looser bound proteins removed: 17% dna. 19% rna: 8% phospholipid membrane, 56% protein, incl. nucleoid associated, h-ns, hu, fis, ihf. Membrane free prep dislodge associated proteins. Nucleoids in both preps unfold w/ (almost anything: heat, dnase + rnase, proteinase, suggest dna, rna and protein needed for nucleosome folding. Nicked loops > single supercoiled domain relaxed by 1 break: topologically distinct loops. 160 breaks / chromosome needed > relax 95% supercoiling: however, need statistical correction could nick same strand again > c. 120 loops / nucleoid 50kb length. 50kb loops > 2 micron nucleoid too big! More recent work suggests smaller: and locus position w/in loop varies between cells. Swai restriction endonuclease expressed: cleave @ known sites. Micro-array study expression of 300 ish supercoiling sensitive genes.
