HMB265H1 Chapter Notes - Chapter 19: Cell Nucleus, Acetyl Group, S Phase
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HMB265H1 Full Course Notes
Dna molecule has coding sequences (exons) + noncoding sequences (introns) Noncoding repetitive dna concentrated in certain regions (telomeres/centromeres) Dna molecules need to fold up to fit in cell nucleus. Interact w/ histone + nonhistone chromosomal proteins to compact. Chromatin = complex of dna + protein. Chromosomes = few pieces of chromatin that behave as unit during cell division. Histones = small proteins (mostly positively charged amino acids lysine and arginine) Positive charge = can bind to dna throughout chromatin. 5 types of histone molecules, appear in chromatin of almost all eukaryotic cells. Modifications on aa exposed on tails of histones h3 and h4. Variation in methylation + acetylation in diff region of chromatin = diff function for those dna regions. Structural (form scaffold = backbone of dna) Several levels of compaction for dna to fit inside cell: The nucleosome is the fundamental unit of chromosome packaging. Then have additional linker dna to connect from one nucleosome to next.