Cell cytoskeleton

• What are the 3 types of filaments cells have?

  Actin microfilaments, microtubules & intermediate filaments
• Where are actin microfilaments found in the cell?


  Outside of cell cytoskeleton
• Where are microtubules found in the cell?


  Middle of cell cytoskeleton
• Where are intermediate filaments found in the cell?


  Nucleus
• What are microtubules made of?

  Alpha & Beta Tubulin
• Which cytoskeleton filament is the biggest?


  Microtubules
• Which cytoskeleton filament is the smallest?


  Actin microfilaments
• What are microtubules stiffer than?


  Actin filaments
• Where are intermediate filaments found?


  Skin
• Where are microtubules found?


  Flagella & cilia
• Intermediate filaments are flexible but resist...


  Strain (twisting & pulling)
• What are flagella?


  • Microtubule based protrusions that grow from centrioles that have moved to cell membrane
  • 1 flagella per cell
  • moves entire cell in 3D corkscrew/wavelike movement
  • In mammals only sperm has flagella
• How are microtubules arranged?


  9 + 2 paired formation
• Functions of actin microfilaments:


  • Form bundles, sheets or networks in cytoplasm
  • Assemble uniformly in muscle cells & interact with myosin proteins to produce muscle contraction
• Where do sperm get energy for motility?


  • Derived from metabolism of fructose carried in seminal fluid
  • Takes place in mitochondria in sperm's midpiece
• What are cilia?


  • Small projections on cell surface (e.g, respiratory tract & female reproductive tract)
  • Motile & beat in coordinated fashion (power stroke vs recovery stroke)
  • moves mucus & trapped particles away from lungs
  • Found on pseudostratified columnar epithelium
• Functions of intermediate filaments:


  • Structural support & mechanical resistance of cell (stop compression)
  • extend nerve cells
  • stable & made of many proteins
• Functions of microtubules:


  • Form microtubule organising centres (e.g, centrosomes & basal bodies)
  • Responsible for mitotic spindle, cell division & movement for cilia & flagella
  • Support & structure to cytoplasm
  • Transport intercellular materials (organelles & chromosomes)
  • Maintain cell polarity due to - & + ends on filaments
• Basal bodies & centrioles have the same...


  Structure
• Where do basal bodies occur?


  Ciliated or flagellated cells
• Filaments diagram: