Download
cytoskeleton n.
Skip this Video
Loading SlideShow in 5 Seconds..
Cytoskeleton PowerPoint Presentation
Download Presentation
Cytoskeleton

Cytoskeleton

553 Vues Download Presentation
Télécharger la présentation

Cytoskeleton

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. Cytoskeleton • Network of protein fibers extending throughout the cytoplasm • Function in providing for both structural support and cell motility • Require interaction of the cytoskeleton with motor proteins • Three main kinds of fibers make up the cytoskeleton:

  2. Figure 7.20 The cytoskeleton

  3. Table 7.2 The structure and function of the cytoskeleton

  4. Microtubules • Hollow rods • Composed of globular proteins called tubulins • Functions: • Cellular support • Tracks for organelle movement • Separation of chromosomes during cell division • Involved in the motility of the cell

  5. Figure 7.x3 Actin

  6. Figure 7.x4 Actin and keratin

  7. Centrosomes and centrioles • Centrosome – region located near the nucleus • Centriole – pair of cylindrical structures located in the centrosome of animal cells • Composed of nine sets of triplet microtubules arranged in a ring • May organize microtubule assembly during cell division

  8. Figure 7.22 Centrosome containing a pair of centrioles

  9. Cilia and flagella • Locomotor organelles formed from a specialized arrangement of microtubules • Unicellular eukaryotic organisms are propelled through water by cilia or flagella • Motile sperm cells (animals, algae, some plants) are flagellated • May function to draw fluid across the surface of stationary cells (ciliated cells lining trachea)

  10. Figure 7.23 A comparison of the beating of flagella and cilia

  11. Figure 7.23x Sea urchin sperm

  12. Figure 7.21 Motor molecules and the cytoskeleton

  13. Figure 7.24 Ultrastructure of a eukaryotic flagellum or cilium

  14. Figure 7.25 How dynein “walking” moves cilia and flagella

  15. Microfilaments (actin filaments) • Solid rods • Composed mainly of proteins called actin • Function: • Helps supports the cell’s shape • Participate in muscle contraction • Responsible for localized contraction of cells (dividing animal cell)

  16. Microfilaments function (cont.) • Elongation and contraction of pseudopodia during amoeboid movement • Involved in cytoplasmic streaming found in plant cells • Cytoplasmic streaming (cyclosis) – flowing of the entire cytoplasm around the space between the vacuole and plasma membrane in a plant cell

  17. Figure 7.26 A structural role of microfilaments

  18. Figure 7.27 Microfilaments and motility

  19. Intermediate filaments • More permanent than microtubules or microfilaments • Constructed from keratin subunits • Function: • Specialized for bearing tension • Reinforce cell shape • Fix organelle position