BIOB10H3 Lecture Notes - Lecture 10: Cytoskeleton, Keratin, Cell Cortex
23 Sep 2016
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Document Summary
8nm diameter filaments: compared to 25nm microtubules. Microfilaments have polarity: end: pointed end, + end: barbed end. Polymerization of f-actin: actin monomers can be added to either end. When the concentration of monomers is high: occurs preferentially at the plus (+) end or barbed end. Occurs even when monomer concentrations are very low: requires energy. Hydrolysis of atp occurs sometime after polymerization. Similar to gtp hydrolysis by tubulin during mt assembly. Depolymerization of f-actin: occurs preferentially at the minus (-) end or pointed end, actin is constantly assembling and disassembling. As monomers are added preferentially to one end and removed preferentially from the other end: it appears as if monomers are moving towards one end (-) end, known as treadmilling. Myosins are motors that move along f-actin: move towards the plus (+) or barbed end, use atp to drive movement. Composed of: 1 pair of heavy chains.
