Question

Calcium ions bring about muscle contraction through

• A. Activation of myosin ATP-ase
• B. Exposing active sites of actin filaments
• C. Mobilisation of food reserve
• D. Both A and B

Answer 1

The correct option is A Activation of myosin ATP-ase

• The muscle contraction cycle is triggered by calcium ions binding to the protein complex troponin, exposing the active-binding sites on the actin.
• ATP can then attach to myosin, which allows the cross-bridge cycle to start again; further muscle contraction can occur.
• Cardiac myosin activators stimulate myosin ATPase, thereby increasing force generation. Hence, Calcium ions bring about muscle contraction
• through Activation of myosin ATP-ase.

So, the correct answer is 'Activation of myosin ATP-ase'.