Question 1:

Which molecule binds to calcium ions during muscle contraction?

Explanation: Troponin is the molecule that binds to calcium ions during muscle contraction. Calcium binding to troponin causes a conformational change that allows myosin to bind to actin and initiate muscle contraction.

Question 2:

Which protein forms the cross-bridges during muscle contraction?

Explanation: Myosin is the protein that forms the cross-bridges during muscle contraction. It binds to actin and undergoes a conformational change to generate force and cause muscle contraction.

Question 3:

What is the role of ATP in muscle contraction?

Explanation: ATP provides energy for the power stroke of myosin. When ATP binds to myosin, it is hydrolyzed into ADP and inorganic phosphate, releasing energy that allows myosin to undergo a conformational change and generate force for muscle contraction.

Question 4:

Which filament slides towards the center of the sarcomere during muscle contraction?

Explanation: Actin filaments slide towards the center of the sarcomere during muscle contraction. The cross-bridges formed by myosin interact with actin and pull the actin filaments towards the center, causing the sarcomere to shorten.

Question 5:

Which regulatory protein covers the myosin binding sites on actin in a relaxed muscle?

Explanation: Tropomyosin is the regulatory protein that covers the myosin binding sites on actin in a relaxed muscle. When calcium binds to troponin, it causes a conformational change that allows tropomyosin to move and expose the myosin binding sites on actin, initiating muscle contraction.