Lecture 14 Microtubule Motors

Lecture 14 Microtubule Motors - IPHY 3060 Lecture 14:...

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IPHY 3060 Lecture 14: Microtubule Motors
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Key Points from Earlier 3 different cytoskeletal filament systems exist in cells, each with its own functions Actin filaments along with myosin motors are responsible for muscle contraction, cell migration, and cytokinesis
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Microtubules Form 25 nm filaments Formed from polymerization of tubulin dimers Very dynamic—can shrink or grow extremely rapidly Have polarity– (+) and and (-) end Microtubules have organizing structures to assist in their functions
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Show videos—microtubule dynamics
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Microtubules are usually arranged with the (-) end toward the center of the cell and the (+) end toward the outside of the cell
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Microtubule Organizing Structures Centrosome —MTOC responsible for forming mitotic spindle during mitosis Spindle Poles —MTOC in mitotic cell MTOC —responsible for forming microtubules in axons and dendrites of neurons Basal body --complex at the base of a flagellum or cilium that organizes/orients flagellar/ciliary microtubules
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Microtubule Assembly β Step 1a: dimer formation
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Factors Influencing Microtubule Assembly and/or Stability Critical concentration of tubulin—above this, microtubules polymerize, below it, they disassemble—affects assembly GTP hydrolysis by tubulin monomers—GDP- bound tubulin monomers have rapid dissociation from microtubule, microtubule will shrink-- decreases stability Microtubule associated proteins—can affect assembly and/or stability Microtubule poisons—can affect microtubule stability
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Microtubule Poisons Colchicine—depolymerizes microtubules leading to decreased stability Taxol—increases stability of microtubules Interfering with either process interferes with mitosis and cell proliferation
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What is the function of microtubules?
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Functions of Microtubules Movement of vesicles and other organelles Separation of chromosomes during mitosis Cell movement through beating of cilia or flagella
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Microtubule Motor Proteins:
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Microtubule Motor Proteins: Proteins which convert chemical energy into mechanical force to move cells and structures along microtubules
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Microtubule-Associated Motor Proteins Kinesin Dynein
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This note was uploaded on 08/11/2010 for the course IPHY 3060 taught by Professor Allen,davi during the Fall '09 term at Colorado.

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Lecture 14 Microtubule Motors - IPHY 3060 Lecture 14:...

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