Muscle Contraction

Question 1

Sliding filament mechanism

Answer 1

Actin filaments slide along the myosin filaments during each power stroke of a myosin head.

1. Calcium ions cause tropomyosin to move away from myosin binding sites on actin
2. Myosin heads attach to a binding site on actin, forming a actinomyosin bridge
3. ADP and Pi are released from myosin head
4. ATP binds to myosin head and myosin head detaches from actin.
5. ATP is hydrolysed into ADP and Pi and myosin head returns to its starting position.