BIOL 1090 Study Guide - Comprehensive Final Guide: Dynamic Structures, Hbb, Pectin
29 Nov 2016
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Second level of condensation:- more folding or supercoiling/twisting: the way the 30nm fibre looks has two options. Depends on the method used to visualize it. Zig-zag is commonly accepted: dna wraps about 3 times around each histone, histone 1 protein (h1) attaches to each histone, histones then coil together to form the solenoid. Attaching the 30nm fibre in many positions. 30nm is the basic structural unit of the metaphase chromosome. Folds and loops in a very similar way to eukaryotic dna (fig 9. 15: circular chromosome folded chromosome (flower shape) supercoiled, folded chromosome (telephone wire flower shape) We have mitochondrial genomes: double stranded, circular. Chloroplasts also have a set of genes dedicated to the processes of what goes on in the organism. Gives evidence to endosymbiotic theory: one cell lived inside another to live in harmony. Smaller cell had advantages (protection, etc. ) but couldn"t live outside of other organism (obligate parasite?) Because of this, we still have some circular dna.
