Question

20) In order for high force cross bridges to form in contracting skeletal muscle, calcium must A) phosphorylate the troponin to move the tropomyosin. B) bind to calmodulin to phosphorylate the myosin. C) phosphorylate the tropomyosin which moves it. D) bind to tropomyosin which moves the troponin. E) bind to troponin which moves the tropomyosin.

Answer 1

Answer:

E. bind to troponin which moves the tropomyosin

Explanation:

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