PHYSIOLOGY
SLIDING FILAMENT MODEL
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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the actin myofilament.
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the myosin myofilament.
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the tropomyosin molecule.
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the troponin molecule.
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Detailed explanation-1: -(2) Calcium binds to troponin C, which induces a conformational change in the troponin complex. This causes tropomyosin to move deeper into the actin groove, revealing the myosin-binding sites.
Detailed explanation-2: -When calcium binds to troponin, the troponin changes shape, removing tropomyosin from the binding sites. The sarcoplasmic reticulum stores calcium ions, which it releases when a muscle cell is stimulated; the calcium ions then enable the cross-bridge muscle contraction cycle.
Detailed explanation-3: -On activation, Ca2+ binding to troponin leads to an azimuthal motion of tropomyosin around the actin filament that uncovers the myosin binding sites, permitting the actin-myosin interaction that drives contraction (5–7).