Lecture13

Lecture13 - 02.16.11 Lecture 12 - The actin cytoskeleton...

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02.16.11 Lecture 12 - The actin cytoskeleton
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Actin filaments allow cells to adopt different shapes and perform different functions Villi Contractile bundles Finger-like protrusions Contractile ring
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Actin filaments are thin and flexible 7 nm in diameter Less rigid than microtubules Plus end - fast growing Minus end - slow growing Monomers polymerize into a helical chain
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Actin and microtubules polymerize using similar mechanisms Monomeric actin binds to ATP Upon polymerization, actin ATPase activity cleaves ATP to ADP ATP hydrolysis acts as a molecular “clock” Older actin filaments with ADP are unstable and disassemble
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Actin architecture and function is governed by actin-binding proteins
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Example: actin in microvilli
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Example: actin in the cell cortex
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Actin polymerization can produce “pushing” forces • Polymerization at the front of a cell pushes the leading edge forward • Phagocytosis - formation of pseudopods • Intracellular movement and cell-to-cell spreading of pathogens
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During cell migration, actin polymerization pushes the leading edge forward
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Actin polymerization drives protrusion of the cell membrane Lamellipodia Filopodia
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Lamellipodia are composed of branched networks of short filaments 11
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membranes in lamellipodia
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This note was uploaded on 05/26/2011 for the course BIO 205 taught by Professor Reed during the Spring '11 term at UNC.

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Lecture13 - 02.16.11 Lecture 12 - The actin cytoskeleton...

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