PHYSIOLOGY
MUSCLE CONTRACTION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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When myosin pulls on actin.
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To cause myosin to let go of actin.
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When myosin moves back to its “loaded spring” position.
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None of the above
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Detailed explanation-1: -At the end of the power stroke, the myosin is in a low-energy position. After the power stroke, ADP is released, but the cross-bridge formed is still in place. ATP then binds to myosin, moving the myosin to its high-energy state, releasing the myosin head from the actin active site.
Detailed explanation-2: -ATP binding causes the myosin head to detach from the actin. After this occurs, ATP is converted to ADP and Pi by the intrinsic ATPase activity of myosin. The energy released during ATP hydrolysis changes the angle of the myosin head into a cocked position. The myosin head is now in position for further movement.
Detailed explanation-3: -ATP is not required for forming the cross-bridges between myosin and actin filaments. C. Hydrolysis of ATP provides energy for myosin head to move along actin filaments and the binding of ATP to myosin head allows the detachment of myosin from actin filaments.