Answer :
Final answer:
One molecule of ATP is used each time a myosin head pivots and pulls on an actin filament during muscle contraction, enabling the myosin head to complete a power stroke and prepare for the next cycle.
Explanation:
During muscle contraction, the interaction between myosin and actin involves the cyclic hydrolysis of adenosine triphosphate (ATP). As the myosin head pivots and pulls on an actin filament, one ATP molecule undergoes hydrolysis, converting it into adenosine diphosphate (ADP) and inorganic phosphate (Pi). This hydrolysis provides the energy required for the myosin head to move into a "cocked" position. Subsequent release of ADP and Pi results in a power stroke, causing the myosin head to pull the actin filament.
For the myosin head to detach from actin and prepare for another contraction cycle, another ATP molecule must bind to it. This cyclic process of ATP hydrolysis and binding is fundamental to the molecular mechanism of muscle contraction, ensuring the repetitive engagement and release of myosin with actin during the contractile events in skeletal muscle.
