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Unformatted text preview: BIO 320 - CELL BIOLOGY 2009 Summer A. De Lozanne Lectures 11 14 The Cytoskeleton Reading: Alberts, 5th Ed. Pages. Chapter 16 - the following sections: The Self Assembly and Dynamic Structure of Cytoskeletal Filaments: pg 965-991 How Cells Regulate Their Cytoskeletal Filaments: pg 992-1010 Molecular Motors: pg 1010-1025 The Cytoskeleton and Cell Behavior: pg 1025-1030 & 1036-1041 Lecture Outline I. Introduction A. The cytoskeleton is a dynamic structure with many roles. 1. It serves as a scaffold, providing structural support and maintaining cell shape. 2. It serves as an internal framework , organizing organelles within the cell. 3. It assists in movement of materials within the cell and cellular locomotion . 4. It provides anchoring sites for mRNA . 5. It anchors mRNA during translation . 6. It serves as a signal transducer. 7. It is an essential component of the cells division machinery . B. The cytoskeleton is a network of three filamentous structures : 1. microtubules, microfilaments, and intermediate filaments. II. The Study of the Cytoskeleton A. Fluorescent microscopy of live cells locates fluorescently-labeled proteins. B. Video microscopy and in vitro motility assays enable observation of intracellular movements. C. The electron microscope can be used to visualize the cytoskeleton of a treated cell. III. Molecular Motors A. Molecular motors convert chemical energy of ATP into mechanical energy. 1 BIO 320 - CELL BIOLOGY 2009 Summer A. De Lozanne B. Molecular motors move by stepwise , conformational changes corresponding to a mechanical cycle. C. Three categories of molecular motors have been described. 1. Kinesins and . 2. Dyneins move along tracks of microtubules . 3. Myosins move along microfilament tracks. IV. Microtubules A. Structure and composition: 1. Microtubules are hollow cylindrical structures found in the cytoskeleton, mitotic spindle, cilia, and flagella . 2. The microtubule is a polymer made up of globular tubulin subunits arranged in longitudinal rows called protofilaments . 3. Most microtubules contain 13 protofilaments. 4. Heterodimers of - and -tubulin subunits are assembled into tubules with plus (fast- growing) and minus (slow-growing) ends . B. The dynamic properties of microtubules: 1. Microtubules assemble and disassemble readily (dynamic instability )....
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- Spring '08