Question

Which step of the cross bridge cycle is mediated by the ATPase function of myosin, wherein ATP is hydrolyzed to ADP and Pi?

A) Cross Bridge Formation
B) Power Stroke
C) Cross Bridge Detachment
D) Cocking of the Myosin Head

Answer 1

The correct answer is option D. The ATPase function of myosin where ATP is hydrolyzed to ADP and Pi corresponds to the cocking of the myosin head in the cross bridge cycle of muscle contraction.

Step-by-step explanation:

Within the cross bridge cycle of muscle contraction, the ATPase function of myosin, where ATP is hydrolyzed to adenosine diphosphate (ADP) and inorganic phosphate (Pi), is specifically related to the cocking of the myosin head.

Initially, the myosin head attaches to actin forming a cross bridge. During the power stroke, the myosin head bends while ADP and Pi are released, and the actin filament is pulled towards the center of the sarcomere. Subsequently, another ATP molecule binds to the myosin head, which then causes the cross bridge to detach. This binding of ATP to the myosin head also initiates the hydrolysis of ATP into ADP and Pi, re-energizing and repositioning the myosin head into the cocked position, ready to begin another cycle of muscle contraction.