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Chapter 6B

Chapter 6B. The Cytoskeleton. Intro. The cytoskeleton is a network of fibers extending through the cytoplasm Maintains __________________. Motility: cell location and movement of cell parts Involves cytoskeleton and motor molecules

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Chapter 6B

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  1. Chapter 6B The Cytoskeleton

  2. Intro • The cytoskeleton is a network of fibers extending through the cytoplasm • Maintains __________________. • Motility: cell location and movement of cell parts • Involves cytoskeleton and motor molecules • Ex. cilia, flagella, muscle cell contraction, vesicle movement, phagocytosis -Regulation of biochemical activities in the cell

  3. Microtubules • Thickest, cytoplasm of eukaryotic cells. • Straight, hollow, made of globular protein ___________________________. • Elongates by: • Can be a track along which molecules move (Golgi: secretory vesicles) • Separation of chromosomes in cell division

  4. http://www.youtube.com/watch?v=PvDlilBgoSs

  5. Cilia • Either move _________ or move __________. • Large numbers on cell surface • Alternate power and recovery strokes, generate force _______________ to the cilium’s axis

  6. Flagella • Usually one to a few per cell; longer than cilia • Undulating motion that generates force in same direction as flagellum’s axis

  7. “9-2” pattern • Found in both cilia and flagella • ___ doublets of microtubules form a ring, in the center are 2 microtubules • Have radial spokes that connect doublets of outer ring to the center of the cilium or flagellum; each doublet also has pairs of evenly spaced ______ arms; whole assembly anchored by a __________________. • Dynein: protein responsible for movement • Dynein walking: like cat up a tree: arms attach to ___________, pull, release and reattach

  8. http://www.tutorvista.com/content/biology/biology-iii/cell-organization/nonmembranous-cell-organelles.phphttp://www.tutorvista.com/content/biology/biology-iii/cell-organization/nonmembranous-cell-organelles.php

  9. Microfilaments • AKA actin filaments, solid rods • Built from actin, a globular protein, twisted double chain of actin subunits. • Use pulling forces to bear tension for structural support (cell shape) • Gives cortex (outer cytoplasmic layer) ____________ consistency of a gel. • Make up _____________: delicate projects that increase cell surface area

  10. http://www.cartage.org.lb/en/themes/sciences/zoology/animalphysiology/anatomy/animalcellstructure/microfilaments/microfilaments.htmhttp://www.cartage.org.lb/en/themes/sciences/zoology/animalphysiology/anatomy/animalcellstructure/microfilaments/microfilaments.htm

  11. Microfilaments cont. • Cell motility: muscle cell contractions: thousands of microfilaments arranged parallel to one another, interdigitated with thicker filaments made up of the protein myosin. Contraction: actin and myosin slide past each other, shortening the cell • Pseudopodia( _________): extend and contract through reversible assembly of actin subunits into microfilaments which convert cytoplasm from ____ to _____. • Cytoplasmic streaming: circular flow of cytoplasm within the cell

  12. http://www.youtube.com/watch?v=dnY3ic_UYps

  13. Intermediate Filaments • Size in between microtubules and microfilaments • Made up of _________ • More permanent structural support • Ex. Lamina in nuclear envelope • Ex Supports _____ of nerve cells

  14. http://www.tutorvista.com/content/biology/biology-iii/cell-organization/nonmembranous-cell-organelles.phphttp://www.tutorvista.com/content/biology/biology-iii/cell-organization/nonmembranous-cell-organelles.php

  15. Cell Surfaces • 1. Cell wall: maintains shape, regulates water level *Made up of matrix of microfibrils composed of cellulose, embedded in polysaccharides and proteins. Young plants have primary cell wall between walls, older plants hardens primary wall or adds secondary cell wall. • Extracellular Matrix: * Made up of glycoproteins, collagen, embedded in network of proteoglycans, communicate signals to microfilaments in the cytoskeleton

  16. Cell Junctions • 1. Plasmodesmata: channels through cell walls in _______ cells. • 2. Tight junctions: fused to neighboring cells • 3. Desmosomes: ______ that fasten cells together (reinforced by intermediate filaments) • 4. ____ junctions: Cytoplasmic channels between adjacent cells

  17. http://webanatomy.net/histology/epithelial_histology.htm

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