How Does Tropomyosin Control Muscle Contraction

Question

How does tropomyosin control muscle contraction?
A) It provides a bridge between actin and myosin.
B) It provides a site where ATP can be utilized.
C) Changes in its position expose myosin-binding sites on actin filaments.
D) It transmits electric charge to the filaments.
E) Changes in its shape cause membrane channels to open.

Accepted Answer

Tropomyosin controls muscle contraction by regulating the exposure of myosin-binding sites on actin filaments. When calcium ions bind to the troponin complex, it causes a conformational change in tropomyosin, exposing the myosin-binding sites and allowing for cross-bridge formation between actin and myosin, leading to muscle contraction. Without this regulation, the muscle fibers would remain in a contracted state.