Cytoskeleton: Motility and Mitosis

Cytoskeleton: Motility and Mitosis

1. STRUCTURE

   • Filapodia
     • Extension from the cell which detect the enviorment around the cell
       • contain actin filament
   • Stress fibres
     • Hold the cell together and keep its shape as it moves, they stretch and contract once the cell as extended
       • Also bundles of actin
   • Focal Adhesion
     • Like mini feet, found on the bottom of cells, they elevate the cell and links the cytoskeleton to the outside
   • Lamelapodia
     • Bundling of actin filament together, which cause the cell to move (treadmilling)

2. HOW DO CELLS MOVE?

   • The actin filament subunits line up parallel at the leading edge,
   • One end polymerised whilst other broken down, this is called treadmilling (lost at -, added on +)
     • Many F actin do this at the same time
   • The filament moves forward whilst the actin filament remains the same size

3. WHY IS CELL MOTILITY NEEDED?

   • Cell Migration
     • Chemotaxis
       • Destroying pathogen
     • Tissue formation
       • Repair of cells
     • Cancer
       • Metastasis

4. TERMINOLOGY

   • Leading Edge
     • Front of the cell
   • Lagging end
     • Back of the cell

5. MITOSIS

   • Microtubules
     • The are formed from spindle fibre and they attach to the centrosome of the chromosone, one from each side on every chromosone. They pull at the same force and chromosones are pulled apart. They then depolarise and get shorter moving chromosones to opposite sides of the cell
   • At cytokenesis the actin filament strangulate inbetween the nuclei by becoming shorter (depolarisation)

6. INTERGRINS

   • Receptors which connect the ECM and the cytoskeleton
     • They bind to matrix molecules causing them to become activated, they relay activation into the cytoplasm of the cell

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