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Ch 8 bio notes.docx

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BIOL 1000
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Ch 8 Cell Cycle Prokaryotic –cell cycle - Double in size - Replicate circular chromosome, move each two daughter chromosomes into its own progeny cell - Binary fusion – cell division - 1. Cells grow for some time before initiating DNA synthesis - 2. Chromosomes replicated, and separated to opposite ends of cell - 3. The membrane pinches together between them and two daughter cells are formed - Replication of bacterial chromosome starts at origin of replication , the ori is ine the middle of the cell once ori has been duplicated they move to opposite ends of cell - Cytoplasmic division is associated with an inward constriction of cytokinetic ring of cytoskeletal proteins - Most prokaryotic have a single chromosome where as eukaryotics have many chromosomes - Advanced form of mitotic apparatus is seen in yeats – a spindle of microtubules (made polymerized tubulin proteins) forms and chromosomes segregate to daughter nuclei without disassembly/reassembly of nuclear envelope Eukaryotes - 2 copies of chromosome in nuclei their chromosome complement is diploid (2n) - Mostly microorganisms may only have one copy of each type of chromosome in nucleus. So chromosome complement is haploid (n/2) - Replication of DNA of each individual chromosome creates two new identical molecules sister chromatids held in centromere til mitosis - Equal distribution of daughter chromosomes to each of the two cells result from cell division chromosome segregation - Ph 165 drosphilia – fruit fly Mitosis - Interphase o First and longest face phase o Cell grows and replicates DNA in prep for mitosis (M phase) o G1 phase: cell makes various RNA’s, proteins and other cellular molecules NOT nuclear DNA – G stands for gap (absence in DNA synthesis) o S phase: s stands for synthesis (of DNA) – cell duplicates the chromosomeal proteins as well as DNA and contines the synthesis of other cellular molecules o G2 phase: - secod gap (no DNA synthesis) cell continues to synthesize RNA and proteins o Chromosomes relatively loose n nucleus o G1 varies in length in time Once DNA synthesis occurs mammalian take 10-12 hours through s-phase 4-6 hours in G2 phase, 1-4 complete mitosis o G0 phase when cells stop dividing happens In humans nervous system when fully mature - Prophase o Chromosomes begin to condense into rod-like structures o Nucleolus becomes smaller (disappears most species) this = shut down of RNA synthesis o In cytoplasm the mitotic spindles begin to form between two centromeres start migrating towards opposite ends to form spindle poles o Nuclear envelope breaks down - Prometaphase o Spindle microtub
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