DernburgLecture6_2-10-10_forprinting

DernburgLecture6_2-10-10_forprinting - 3 major classes of...

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3 major classes of cell structural polymers: Chapter 17 Today’s lecture Chapter 18 Friday’s lecture keratins, lamins, vimentin, etc. Cell shape and rigidity Cytokinesis (cell division) Cell polarity Muscle contraction Actin filaments are required for. .. Cell movement (normal and malignant) A motile (moving) cell fixed and stained for F-actin the “leading edge” A variety of actin structures Actin is an ATPase. Its assembly and disassembly are driven by energy from ATP. Note: on Friday we’ll focus on tubulin, which is a GTPase.
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1) lag due to kinetic barrier to nucleation 2) growth 3) equilibrium [polymer] lag growth equilibrium time Polymer assembly kinetics in vitro definition: rate of subunit addition = rate of loss polymer grows as time proceeds free subunit concentration drops until K on [C] = K off [C] = critical concentration Cc (M -1 sec -1 [M] = sec -1 ) Addition of pre-formed nuclei eliminates the initial lag phase Actin (and tubulin) polymers have POLARITY = nonequivalence of two ends - allows cell to generate asymmetric structures and shapes Actin decorated with myosin subfragment 1 (“barbed” appearance is due to myosin binding) - motor proteins recognize polymer asymmetry, providing directionality for force production, moving cargo - basis of directional motility
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This note was uploaded on 02/16/2010 for the course MCB 74282 taught by Professor Professordernburg during the Spring '10 term at Berkeley.

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DernburgLecture6_2-10-10_forprinting - 3 major classes of...

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