The ion necessary for cross-bridging is:
A) iron.
B) sodium.
C) potassium.
D) calcium.

Question

Quizplus · Accepted Answer

The ion necessary for cross-bridging is calcium. During muscle contraction, calcium ions bind to the protein troponin, which causes a conformational change in the protein tropomyosin, leading to exposure of the myosin-binding sites on actin filaments. This allows the cross-bridges between actin and myosin to form, leading to muscle contraction. Therefore, calcium is the necessary ion for cross-bridging.

The Ion Necessary for Cross-Bridging Is