Question

During an action potential, calcium is released into the sarcoplasm, near the actin and myosin molecules.Which of the following is the best explanation of what the calcium does?

• A. The calcium binds to the actin and myosin and makes them work together.
• B. The calcium breaks apart ATP to ADP and P.
• C. The calcium removes the tropomyosin block.
• D. The calcium causes the release of acetylcholine.

Answer 1

The correct option is C

The calcium removes the tropomyosin block.

calcium ions bind to troponin, causing conformational changes in troponin that allow tropomyosin to move away from the myosin-binding sites on actin. Once the tropomyosin is removed, a cross-bridge can form between actin and myosin, triggering contraction.