BIO 121 Lecture Notes - Lecture 18: Tunxis Community College, Spindle Apparatus, Myosin
23 Nov 2020
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Actin polymerization drives pm protrusion in the cell cortex that results in crawling. Branched actin polymerization mediated by arp 2/3 pushes membrane forwards. Contractile bundles provides traction, rear contraction helps cell detach from surface+move. Myosins use energy of atp hydrolysis to move along actin filaments. Myosin 1 and myosin ii move towards (+) end of f-actin. Muscle actin+myosin generate contraction by sliding over one another. Head of myosin ii walks along actin filament through atp dependent cycle on conformational change. Cell growth (duplication of organelles, vol cytoplasm increased) Post mitotic state : senescent (permanent arrest) or quiescent (temporary arrest) S = from initiation of dna synthesis (iids) to completion of synthesis. Completion of dna synthesis to beginning of cell division. Replicated sister chromatids condense to facilitate segregation by mitotic spindle. Used to measure dna content of cells. Cells stained with fluorescent dye that binds to dna. Amount of dna is proportional to fluorescence emitted.
