Which cytoskeletal component is primarily involved in muscle contraction and intracellular movement?

• A. Provide energy for the cell
• B. Involved in muscle contraction and intracellular movement; form part of the cytoskeleton
• C. Store genetic material
• D. Transport lipids across membranes

Answer: (B)

Actin filaments (microfilaments) are the cytoskeletal component most closely tied to muscle contraction and intracellular movement. In muscle, contraction happens via the sliding filament mechanism: myosin motor proteins attach to actin filaments and, using energy from ATP, pull on them to shorten the sarcomere and generate force. Actin filaments also provide tracks along which motor proteins move cargo inside the cell, enabling intracellular transport of organelles and vesicles. Other options describe roles like energy production, storing genetic material, or lipid transport, which aren’t the primary functions of the cytoskeleton in contraction and intracellular movement. So actin filaments are the best-fit component.