Cell Movement and Cytoskeleton Structure

Cell Movement and Function

• Cell movement is the ability of cells to alter their position or shape, vital for tissue growth & differentiation.
• Crucial in multicellular organisms for embryonic development, adult tissue repair, and immune response to pathogens.
• Uncontrolled cell movement can signify cancer.

Mechanisms of Cell Movement

• Cell movement employs ATP-dependent mechanisms:
  • Specialized motor proteins (kinesins & dyneins) interacting with microtubules.
  • Actin microfilaments and myosin motor molecules.

Cytoskeleton Structure

• The cytoskeleton is composed of microtubules, actin filaments, and intermediate filaments.

Microtubules

• Microtubules (MTs) are the largest cytoskeletal filaments.
• Functions: mitosis, cell motility, intracellular transport, maintaining axons and cell form.
• Found in all eukaryotic cells.

Protofilaments

• Protofilaments are components of microtubules.
• A singlet microtubule in mammals is composed of 13 protofilaments.

Intermediate Filaments

• Keratin is an essential protein for animal structures (hair, skin, nails, horns).
• Primarily provides mechanical strength to cells, supporting against stress.
• Less dynamic than actin filaments or microtubules.
• Often work with microtubules for strength & support.

Cilia and Flagella

• Cilia and flagella, involved in cell movement, stem from specialized microtubule groupings—basal bodies.
• Composed of microtubules anchored to the plasma membrane.
• Function in fluid movement past cell surfaces (e.g., for water flow).
• In single-celled organisms, they are used for locomotion (e.g., sperm).