Lecture 7 & 8; Movement & Muscle Physiology .pdf - Lecture 7 8 Movement Muscle Physiology Thursday 1 10:06 AM Cytoskeleton Motor Proteins

Lecture 7 & 8; Movement & Muscle Physiology .pdf - Lecture...

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Cytoskeleton & Motor Proteins; MovementCytoskeleton -- protein-based intracellular network composed o(+ and - ends) When filaments grow in length, they can push the filamenmembrane must stretch with it (i)In gut, microvilli surround gut wall; get tiny little bumps toabsorption (ii)Motor protein can carry a vesicle (iii)Neutrophil can move bc it is constantly polymerizing (2 smsense chemical trail that bacteria leaves behind & can adjfilament of actin-myosin complex (iv) Four ways to use the cytoskeleton for movement:Intracellular supporti.Anchored motor protein pulls cytoskeletonii.Cytoskeleton stationary/motor proteins moiii.Complex arrays that allow cytoskeleton elemiv.§Motor Proteins -- enzymes that convert energy from ATP hydrolconformational changesKinesin & dynein(walking proteins) move along tubulin-bMyosin(head-neck proteins) move along actin-based MICMICROTUBULESMade of tubulinGood control to compare other proteins bc can be found Polarized; MTOC has (-) charge and is on the inside / integoutside (plasma membrane) Can transport substances along these roadways via kinesiA.Assembly Monomers: a-tubulin (-) & b-tubulin (+)1.A & B bind together to form tubulin; which is a dimer 2.Dimers continue to bind together to form a protofilamen3.Form sheet & sheet rolls up due to the opposite charges (+) end, we have growth due to addition of polymeGrowth is faster here than (-) end i.(-) end, we have shrinkage of the microtubule ii.4.Factors Affecting Growth/ShrinkageTublin Concentration; high concentration promotes growt1.Lecture 7 & 8: Movement & Muscle Physiology Thursday, May 31, 201810:06 AM
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of microtubules & microfilaments; polarized nts & tubules past the membrane & o increase amount of surface area for mall molecules make 1 large molecule); can just cell shape to follow it ALSO think sliding obilements to slide over one another lysis to mechanical energy; undergo based MICROTUBULESCROFLIAMENTS in many animals w/ multiple isoformsgral proteins has (+) charge and is on the in (+) & dynein (-)ntersth
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Critical concentration lower on (+) than (-) §Need less tubulin on (+) so lower concentrations arto (-) end§(+) end grows faster §Need more tubulin on (-) so the concentration thaton (-) end, so shrinkage is promoted §(-) end shrinks§Temperature; low temperature promotes shrinkage MAPs (Microtubule-Associated Proteins); stabilize/destabAnchor microtubule to the cell surface§Like a lock, to keep tubule stable§Unlock it, tubule shrinks towards MTOC (inside the§Dynamic Instability; random growth/shrinkage of a microDepends on GTP hydrolysis of B-tubulin§GTP removed (hydrolysis to GDP) = alters ability to§GTP intact = allows it to grow §Chemicals; change ability of microtubule to grow & shrinkTaxol -- permanent stabilization of tubule; its stuck§Cholchicine -- stops tubulin from growing by inhibibigger molecule; in this case, dimer become protof§APPLICATIONS: cancer treatments -- stopping cancof their microtubules §Movement Along Microtubules KINESIN towards (+) Carries vesicles w/ chemical messengers (ie. neuro
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