Microfilaments and Intermediate Filaments

Microfilaments

• Location: Found in the cytoplasm
• Composition: Composed of a protein called actin
  • Actin molecules join to form actin polymers
  • Actin polymers twist to form actin filaments
• Function: Involved in the gross movement of the cell
  • Dynamic Nature: Can lengthen and shorten frequently
    • Lengthening: Actin polymerization
    • Shortening: Actin depolymerization
• Role in Cell Movement:
  • Cell Division: Helps pinch the cell to form two separate cells
  • Amoeba Movement: Assists in moving pseudopods to capture food

Intermediate Filaments

• Composition: Made of various types of proteins
  • Proteins form polymers that twist together into filaments
• Nature: Permanent once formed
  • Unlike microtubules and microfilaments, do not change frequently
• Function: Provides structural support and resists mechanical stress
  • Comparable to mattress springs which help maintain shape under stress