Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

The Cytoskeleton

4,083 views

Published on

overview of cellular cytoskeleton

Published in: Education, Technology
  • Be the first to comment

The Cytoskeleton

  1. 1. Cellular Structural Support
  2. 2. <ul><li>a network of fibers extending throughout the cytoplasm </li></ul>Cytoskeleton
  3. 3. <ul><li>a network of fibers extending throughout the cytoplasm </li></ul>Cytoskeleton microtubules
  4. 4. <ul><li>a network of fibers extending throughout the cytoplasm </li></ul>Cytoskeleton microtubules intermediate filaments
  5. 5. <ul><li>a network of fibers extending throughout the cytoplasm </li></ul>Cytoskeleton microtubules intermediate filaments microfilaments
  6. 6. <ul><li>maintains shape of the cell. </li></ul>Some functions:
  7. 7. <ul><li>maintains shape of the cell. </li></ul><ul><li>provides anchorage for organelles and cytosolic enzymes </li></ul>Some functions:
  8. 8. <ul><li>maintains shape of the cell. </li></ul><ul><li>provides anchorage for organelles and cytosolic enzymes </li></ul><ul><li>provides tracks for movement of organelles </li></ul>Some functions:
  9. 9. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
  10. 10. <ul><li>cilia & flagella </li></ul><ul><li>centrioles </li></ul>Microtubules
  11. 11. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig. 7.22 In animal cells, the centrosome has a pair of centrioles , consisting of microtubules arranged in a ring. During cell division the centrioles replicate.
  12. 12. <ul><li>Microtubules are the central structural supports in cilia and flagella . </li></ul>Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig. 7.2
  13. 13. <ul><li>A flagellum has an undulatory movement </li></ul>Fig. 7.23a
  14. 14. <ul><li>Cilia move more like oars </li></ul>
  15. 15. <ul><li>In spite of their differences, both cilia and flagella have the same ultrastructure. </li></ul><ul><ul><li>Both have a core of microtubules sheathed by the plasma membrane. </li></ul></ul>
  16. 16. <ul><li>The bending of cilia and flagella is driven by the arms of a motor protein, dynein . </li></ul><ul><ul><li>Addition to dynein of a phosphate group from ATP and its removal causes conformation changes in the protein. </li></ul></ul><ul><ul><li>Dynein arms alternately grab, move, and release the outer microtubules. </li></ul></ul><ul><ul><li>Protein cross-links limit sliding and the force is expressed as bending. </li></ul></ul>Fig. 7.25
  17. 17. <ul><li>solid rods of protein called actin used in: </li></ul>Microfilaments Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
  18. 18. <ul><li>solid rods of protein called actin used in: </li></ul>Microfilaments Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings muscle cell contraction
  19. 19. <ul><li>solid rods of protein called actin used in: </li></ul>Microfilaments Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings muscle cell contraction extension of pseudopodia
  20. 20. <ul><li>solid rods of protein called actin used in: </li></ul>Microfilaments Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings muscle cell contraction extension of pseudopodia cytoplasmic streaming
  21. 21. <ul><ul><li>Myosin molecules walk along the actin filament, pulling stacks of actin fibers together and shortening the cell. </li></ul></ul>
  22. 22. <ul><li>In other cells, these actin-myosin aggregates are less organized but still cause localized contraction. </li></ul><ul><ul><li>A contracting belt of microfilaments divides the cytoplasm of animal cells during cell division. </li></ul></ul><ul><ul><li>Localized contraction also drives amoeboid movement. </li></ul></ul><ul><ul><ul><li>Pseudopodia , cellular extensions, extend and contract through the reversible assembly and contraction of actin subunits into microfilaments. </li></ul></ul></ul>Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig. 7.21b
  23. 23. <ul><li>In plant cells actin-myosin interactions drive cytoplasmic streaming . </li></ul><ul><ul><li>This creates a circular flow of cytoplasm in the cell. </li></ul></ul><ul><ul><li>This speeds the distribution of materials within the cell. </li></ul></ul>

×