Cytoskeleton

• What is the cytoskeleton?

  An intricate network of protein filaments

  
• How does the cytoskeleton change as a cell responds to its environment?

  It continuously reorganizes as the cell changes shape
• What are some functions of the cytoskeleton?

  Wound healing, muscle contraction, sperm movement

  
• What are the three types of filaments in the cytoskeleton?

  • Intermediate filaments
  • Microtubules
  • Actin filaments (microfilaments)

  
• What is the primary function of intermediate filaments?

  Provide tensile strength against mechanical stress

  
• Why are intermediate filaments called 'intermediate'?

  Because their diameter is between thin and thick filaments
• How do intermediate filaments contribute to cell structure?

  They are tough and durable, providing support

  
• Where are intermediate filaments found in the cell?

  In the cytoplasm, surrounding the nucleus

  
• What role does the nuclear lamina play in relation to intermediate filaments?

  It provides a mesh of intermediate filaments for support

  
• How do intermediate filaments compare to reinforced concrete?

  They distribute forces to prevent rupture

  
• How many classes of intermediate filaments are there?

  Four classes for different cell types

  
• What is the most diverse type of intermediate filament?

  Keratins found in epithelia and hair
• How do accessory proteins stabilize intermediate filaments?

  They hold bundles together and link to other structures
• What happens to intermediate filaments during cell division?

  They disassemble and reform

  
• What are microtubules?

  Long and stiff hollow tubes

  
• What is the role of microtubules in the cell?

  They provide tracks for moving cell components

  
• How do microtubules contribute to cell division?

  They form the mitotic spindle
• What are microtubules composed of?

  Dimer of α and β tubulin
• What is the structural polarity of microtubules?

  They have a plus end and a minus end
• How do microtubules grow from the centrosome?

  By adding αβ dimers to the γ tubulin ring

  
• What is dynamic instability in microtubules?

  They can suddenly shrink and regrow

  
• What controls microtubule growth?

  GTP hydrolysis

  
• How does selective stabilization affect microtubule organization?

  It allows for organized microtubule systems
• What happens when the GTP cap is lost in microtubules?

  Microtubules shrink due to instability

  
• How do microtubules facilitate intracellular transport?

  They guide traffic within polarized cells

  
• What are motor proteins?

  Proteins that bind to microtubules and actin

  
• How do kinesin and dynein differ in function?

  Kinesins move towards the plus end, dyneins towards the minus end

  
• How do motor proteins use ATP?

  They hydrolyze ATP for energy to move
• What is the structure of actin filaments?

  A twisted chain of identical globular actin

  
• How do actin filaments differ from microtubules?

  They are thinner, more flexible, and shorter
• What is 'treadmilling' in actin filaments?

  Movement of subunits along the filament length
• What role do actin-binding proteins play?

  They regulate polymerization and organization of actin

  
• Where is most actin concentrated in the cell?

  In the cell cortex
• What are the main functions of the cytoskeleton?

  • Provides structural support
  • Facilitates intracellular transport
  • Aids in cell division
  • Enables cell motility

  
• What are the differences between intermediate filaments, microtubules, and actin filaments?

  • Intermediate filaments: Provide tensile strength, stable
  • Microtubules: Hollow tubes, dynamic instability
  • Actin filaments: Thinner, flexible, involved in motility