MCAT Biology Question 154: Answer and Explanation
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Question: 154
4. With which of the following molecules does Ca2+ bind after its release from the sarcoplasmic reticulum to regulate muscle contraction?
- A. Myosin
- B. Actin
- C. Troponin
- D. Tropomyosin
Correct Answer: C
Explanation:
Calcium is released from the sarcoplasmic reticulum into the sarcoplasm. It binds the troponin molecules on the thin filaments, causing the strands of tropomyosin to shift, thereby exposing the myosin-binding sites on the filaments.