Question

During which stage of Excitation-Contraction coupling does Ca²⁺ bind.

A)2
B)6
C)3
D)5

Answer 1

During the excitation-contraction coupling, Ca2+ binds during stage 3. In this stage, calcium ions bind to troponin, exposing the actin-binding sites for cross-bridging with myosin heads.

Step-by-step explanation:

The binding of Ca2+ during the excitation-contraction coupling occurs in stage 3. In this stage, calcium ions bind to troponin, causing a conformational change in the troponin-tropomyosin complex, which exposes the actin-binding sites on the thin filaments, allowing for cross-bridging with myosin heads.