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Multiple Choice
The interaction between which protein and ion initiates muscle contraction according to the sliding filament theory?
A
Tropomyosin and magnesium
B
Actin and sodium
C
Myosin and potassium
D
Troponin and calcium
Verified step by step guidance
1
Understand the sliding filament theory, which explains how muscles contract by the sliding of actin and myosin filaments past each other.
Identify the role of calcium ions in muscle contraction. Calcium ions bind to troponin, a regulatory protein associated with the actin filaments.
Recognize that the binding of calcium to troponin causes a conformational change in the troponin complex.
This conformational change moves tropomyosin away from the myosin-binding sites on actin filaments, allowing myosin heads to attach to actin.
The interaction between troponin and calcium is crucial as it initiates the process of muscle contraction by exposing the binding sites for myosin on the actin filaments.