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BIO 102 Lecture 10 Notes

Contracting muscle revealed loss of myosin heads

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Unformatted text preview: contracting muscle revealed loss of myosin heads along the thick filament helix (heads w ere in motion) In r esting muscle: polarized T-tubule membrane, action potential --> depolarization of membr ane, stimulates opening of calcium release channel T here's a troponin tropomyosin r egulation of muscle contr action, when it binds calcium it falls into the groove (?) - bind to calcium, shifts, and myosin binding sites re exposed Exper iemnt with 2 cell sea urchin embryo: injects a cell w ith an antibody that blocks myosin-II motor activity. cytokinesis is completely inhibited in the injected cell Examples of structural and motor pr operty diversity: -var iations in neck length dictate step size/length (the longer the neck, the longer the step size [exactly 1:1 ratio in additions) -myosins exhibit a wide r ange of motor velocities -some take 1 step -1 kind moves backwards 3 Classes of Microt ubules cytoplasmic (1 little tube), axonemal outer doublet, centriolar tr iplet MTs (3 connected tubes) T he alpha/beta tubulin heterodimer : -both have a Mr of 55k daltons; alpha is 50% homologous to beta -each dimer contains one molecules of non-exchangeable GTP and...
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