PHYSIOLOGY
SYNAPTIC PHYSIOLOGY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Where myosin binds to actin
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Where the calcium crosses into the cytoplasm
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Where calcium binds with troponin
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None of the answers are correct.
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Detailed explanation-1: -A distinctive structure consisting of two globular heads on each myosin molecule which interact in the presence of calcium ions with specific sites on a thin actin filament. The cross-bridges contain ATPase and generate the tension developed by a muscle fibre during a muscle action.
Detailed explanation-2: -Myosin binds to actin at a binding site on the globular actin protein. Myosin has another binding site for ATP at which enzymatic activity hydrolyzes ATP to ADP, releasing an inorganic phosphate molecule and energy. ATP binding causes myosin to release actin, allowing actin and myosin to detach from each other.
Detailed explanation-3: -Once the myosin forms a cross-bridge with actin, the Pi disassociates and the myosin undergoes the power stroke, reaching a lower energy state when the sarcomere shortens. ATP must bind to myosin to break the cross-bridge and enable the myosin to rebind to actin at the next muscle contraction.