The role of calcium in muscle contraction is to
A) release ADP and phosphate from myosin.
B) make it possible for ATP to bind to actin.
C) make it possible for myosin to bind to actin.
D) make it possible for ATP to bind to myosin.

Question

Quizplus · Accepted Answer

Calcium ions bind to the regulatory protein troponin, causing a conformational change that allows myosin heads to bind to actin filaments and initiate muscle contraction. Calcium does not directly affect the binding of ATP to actin or myosin, so choices B and D are incorrect. Choice A refers to the release of ADP and phosphate from myosin during the power stroke of muscle contraction, but this step is not directly influenced by calcium.

The Role of Calcium in Muscle Contraction Is to