Question

Calcium is important in skeletal muscle contraction because it

• A. detaches the myosin head from the actin filament
• B. activates the mysoin ATPase by binding to it
• C. binds to troponin to remove the masking of active sites on actin for myosin
• D. Prevents the formation of bonds between the myosin cross bridges and the actin filament

Answer 1

The correct option is C binds to troponin to remove the masking of active sites on actin for myosin

The muscle contraction cycle is triggered by calcium ions binding to the protein complex troponin, exposing the active-binding sites on the actin. As soon as the actin-binding sites are uncovered, the high-energy myosin head bridges the gap, forming a cross-bridge.