7.4 Dynamic Cytoskeleton

  1. Does the cytoskeleton move around?
    yes, it moves in order to alter the cell's shape, move materials from place to place, and move the entire structure
  2. What are actin filaments (microfilaments)?
    • smallest diameter
    • made of actin
  3. How do actin filaments form?
    individual actin molecules polymerize and coil around each other
  4. Why do actin filaments have a distinct polarity?
    • the strand is asymmetrical
    • the two ends are different and are labeled as plus and minus ends
  5. What is treadmilling?
    when filaments grow and shrink as actin subunits are added or removed from each end of the structure
  6. What else does actin filaments interact with during movement?
  7. What is myosin?
    a motor protein that converts ATP into mechanical energy
  8. What makes the head of the myosin molecule bind to the actin and making it move?
    the ATP binds to the myosin and then is hydrolyzed into ADP
  9. What is cell crawling?
    directional extension of actin filaments pushes the plasma membrane into bulges called "pseudopodia" (false-feet)
  10. What is cytokinesis?
    • cell division in animals
    • actin filaments are arranged in a circle and must slide past each other, pinching the cell in two
  11. What is cytoplasmic streaming?
    directed flow of cytosol and organelles around plant and fungal cells
  12. Intermediate filaments
    • defined by size
    • can consist of different proteins
    • each end is identical
    • purely structural role
  13. Keratin
    • makes up the skin
    • type of intermediate filaments
  14. Nuclear lamins
    • dense mesh under nuclear envelope
    • type of intermediate filaments
  15. microtubules
    • alpha and beta tubulin
    • largest cytoskeletal components (diameter)
    • each end of microtubule has different polarity
    • grow from a microtubule organizing center
    • help with structure and movement
  16. centrosome
    microtubule organizing center in animals
  17. centriole
    • 2 bundles of microtubules within centrosome
    • not needed for microtubule formation (scientists still not sure why they exist o.O)
  18. function of vesicles
    transport material within cells
  19. vesicles travel along ___
    • microtubule "rail road" tracks
    • movement continued as long as ATP was available
    • microtubules necessary for transport
  20. kinesin
    • motor protein that controls movement of vesicles
    • similar to a delivery truck that carries transport vesicles along microtubule tracks
    • "walks" down the microtubule
  21. Bacterial flagella
    • comprised of protein called flagellin
    • rotate flagella like propeller
    • not surrounded by membrane
  22. Eukaryote flagella
    • comprised of microtubules
    • whip back and forth
    • surrounded by plasma membrane
    • 9+2 arrangement
  23. basal body
    • location where axoneme attaches to cell
    • important for growth of axoneme
  24. axoneme
    • 9+2 structure of microtubules
    • isolated structure
  25. Who is Gibbons?
    • studied cilia
    • movement doesn't occur unless ATP is available
  26. dynein
    • a large, motor protein that makes up the arms of the axonemes
    • when ATP attaches to dynein, the end changes shape and the dynein walks up the microtubule
    • causes the flagellum to bend back and forth
Card Set
7.4 Dynamic Cytoskeleton
dynamic cytoskeleton section 7.4