oct 25 cytoskeleton - CYTO SKELETO N P ro v id e s c e ll w...

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1 CYTOSKELETON • Provides cell with mechanical support, and thereby determines its shape. • Mechanism for movement of vesicles and components within cells. • Key in cell motility, the movement of the cell relative to its environment. • Some contribute to cell-cell junctions, connect cells. The Cytoskeleton •cytoplasmic networks of protein filaments and fibers •extends from nucleus to the plasma membrane. •responsible for cell shape, movement within the cell, movement of the entire cell, and some connections between cells •contains three types of elements Actin filaments = microfilaments Microtubules Intermediate filaments •movement powered by ATP hydrolysis, through (a) polymerization and de-polymerization (b) interactions with motor proteins Many cells have a stable shape, and this shape is maintained by a network of cytoskeleton proteins. The epithelial cells of the small intestine have numerous micro- villi on their apical surfaces. Inside its membrane, each microvillus has a core of actin micro- filaments that give the structure its shape. FREEZE-ETCH ELECTRON MICROGRAPH PLASMA MEMBRANE ACTIN MICROFILAMENTS ! urves, Fig. 4.22 Purves, Fig. 4.21 The fibrous proteins that form the cytoskeleton are in fact polymers , each fiber being formed by the multimerization of many thousands of identical protein subunits. The protein subunits that form these polymers differs for 3 major
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This note was uploaded on 02/22/2010 for the course BIO 51980 taught by Professor Buskirk during the Fall '06 term at University of Texas at Austin.

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oct 25 cytoskeleton - CYTO SKELETO N P ro v id e s c e ll w...

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