Multiple Choice
During which step of muscle contraction is the sarcomere at its greatest length?
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9. Muscle Tissue
Steps of Muscle Contraction
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During skeletal muscle contraction, calcium ions (Ca2+) bind to which protein to initiate the sliding filament process?
A
Myosin ATPase active site
B
Actin (G-actin)
C
Tropomyosin
D
Troponin (specifically troponin C)
Verified step by step guidance1
Understand that skeletal muscle contraction is regulated by the interaction of several proteins within the thin filament of the muscle fiber.
Recall that calcium ions (Ca2+) play a crucial role in initiating contraction by binding to a specific regulatory protein associated with the thin filament.
Identify the key proteins involved: actin (G-actin), tropomyosin, and troponin complex (which includes troponin C, I, and T subunits).
Recognize that tropomyosin blocks the myosin-binding sites on actin when the muscle is relaxed, preventing contraction.
Know that when Ca2+ binds to troponin C, it causes a conformational change that moves tropomyosin away from the binding sites on actin, allowing myosin heads to attach and initiate the sliding filament process.
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