7. Cross-Bridge Cycle

What are the five stages of the cross-bridge cycle?

1. Calcium binding, 2. Cross-bridge formation, 3. Power stroke, 4. Detachment, 5. Recovery stroke

What event occurs during stage a of the cross-bridge cycle?

Calcium binding

What is exposed as a result of stage a calcium binding?

Active sites

What occurs during stage b of the cross-bridge cycle?

Cross-bridge formation

What binds to active sites during cross-bridge formation?

Energized myosin heads

What structure is formed when energized myosin heads bind to actin?

Cross-bridge

What chemical release strengthens the bond during the power stroke?

Release of phosphate

In what direction do myosin heads pivot during the power stroke?

Towards M line

What molecule binds to myosin heads to cause detachment in stage d?

ATP

What mechanical action occurs when ATP binds to myosin heads?

Release from actin

What biochemical event occurs during the recovery stroke in stage e?

ATP hydrolysis

What position do myosin heads return to following ATP hydrolysis?

Cocked position