NEET BIOLOGY

Detailed explanation-1: -As the actin is pulled, the filaments move approximately 10 nm toward the M line. This movement is called the power stroke, as it is the step at which force is produced. As the actin is pulled toward the M line, the sarcomere shortens and the muscle contracts.

Detailed explanation-2: -The power stroke pulling myosin along actin filaments during muscle contraction is achieved by a large rotation (≈60°) of the myosin lever arm after ATP hydrolysis. Upon binding the next ATP, myosin dissociates from actin, but its ATPase site is still partially open and catalytically off.

Detailed explanation-3: -The myosin head moves toward the M line, pulling the actin along with it. As the actin is pulled, the filaments move approximately 10 nm toward the M line. This movement is called the power stroke, as it is the step at which force is produced.

Detailed explanation-4: -The power stroke occurs as the thin filament is pulled inward toward the center of the sarcomere. There has been a transfer of energy from the myosin head to the movement of the thin filament. This animation shows ATP binding to the cross bridge, allowing the cross bridge to disconnect from the actin.