Question

The molecular event that occurs immediately after the power stroke is the

A) release of actin from the myosin head.
B) hydrolysis of ATP by the myosin head.
C) release of ADP from the myosin.
D) binding of tropomyosin to the myosin.
E) binding of actin to the myosin.

Answer 1

After the power stroke in muscle contraction, the release of ADP from the myosin head occurs, followed by the binding of new ATP, leading to detachment of the myosin-actin cross-bridge.

Step-by-step explanation:

The molecular event that occurs immediately after the power stroke is the release of ADP from the myosin head. During the power stroke, myosin heads with attached ADP and inorganic phosphate (Pi) bend at their regions, pulling the actin filament along. After the power stroke, another molecule of ATP binds to the myosin head, causing the cross-bridge between actin and myosin to detach. This allows the myosin head to return to its 'cocked' position, ready for another cycle of muscle contraction.