BIOL 2040 Lecture Notes - Lecture 20: Scaffold Protein, Nucleosome, Interphase
Document Summary
Epigenetic inheritance: changes in gene activity that are not based on differences in dna sequence: dna methylation, histone modification, chromosome remodelling (nucleosome position) **dna that is 2m long has to fit into a nucleus that is 10 microns (10um) Compaction: ocatmer of histones allow 147 bp to wrap around it. Core histone: 8 single histone subunits in an f subunit nucleosome. 1st level: histones (nucleosomes) 80bp apart; like beads on a string. 2nd level (h1): allow the 80bp distance to be eliminated (are they fully eliminated or just wound up?) In the interphase, chromosomes are not visible because the dna compact further (this process is called condensation) Scaffold protein condensation (additional activity of scaffolds) chromosome condensation. Aside: sperm is much smaller than the egg because it uses a completely different mechanism of compaction. Involves the protein protamine (different packing tool other than histone) Protamine compaction is tighter than histone compaction; protamine compaction forms solenoids .
