ATP is Used for ________ in Muscle Contraction

Question

ATP is used for ________ in muscle contraction.
A) power stroke
B) the release of calcium from the sarcoplasmic reticulum
C) binding of the myosin and actin
D) none of the above

Accepted Answer

ATP is used for the power stroke in muscle contraction. The power stroke is the step in muscle contraction where the myosin head pivots and pulls the actin filament towards the center of the sarcomere, shortening the muscle fiber. This step requires the hydrolysis of ATP to provide the energy for the myosin head movement. The release of calcium from the sarcoplasmic reticulum and binding of myosin and actin are also important steps in muscle contraction, but they do not directly require ATP for energy.