CYTOSKELETON

• What is the primary function of the cytoskeleton?

  Provides internal protein framework
• What are the main components of the cytoskeleton?

  1. Microfilaments
  2. Intermediate filaments
  3. Microtubules
• What is the diameter of microfilaments?

  Less than 6 nm
• What are microfilaments typically composed of?

  Actin
• Where are microfilaments commonly located in the cell?

  At the periphery of the cell
• What are microvilli and their function?

  • Finger-shaped extensions of cell membrane
  • Core of microfilaments to stiffen and anchor
  • Enhance surface area for absorption
• What is the terminal web in cells?

  Layer inside plasma membrane
• What is the diameter range of intermediate filaments?

  7–11 nm
• What are the characteristics of intermediate filaments?

  Strongest and most durable cytoskeletal elements
• What is the diameter of microtubules?

  Approximately 25 nm
• What protein are microtubules built from?

  Tubulin
• From where do microtubules extend in the cell?

  From the centrosome
• What are centrioles and their function?

  • Cylindrical structures composed of microtubules
  • Two in each centrosome
  • Control movement of DNA during cell division
• What happens to cells without centrioles?

  They cannot divide
• Which types of cells lack centrioles?

  • Red blood cells
  • Skeletal muscle cells
• What are cilia and where are they commonly found?

  Long extensions in respiratory and reproductive tracts
• What are cilia composed of?

  Microtubules
• How are cilia structured?

  • Nine groups of pairs surrounding a central pair
  • Anchored to cell surface with basal body
• What is the function of cilia in cells?

  Beat rhythmically to move fluids
• How do microfilaments, intermediate filaments, and microtubules differ in structure and function?

  • Microfilaments: <6 nm, composed of actin, provide flexibility
  • Intermediate filaments: 7–11 nm, strongest, provide durability
  • Microtubules: ~25 nm, composed of tubulin, provide structure