Question

What is the correct sequence of events in the cross bridge cycle?

• A. Detachment
• B. Formation
• C. Power stroke
• D. Reactivation

Answer 1

The correct sequence of events in the cross bridge cycle is as follows.
Calcium released binds to the troponin and unblocks the actin sites. The myosin head is activated when ATP binds to it. Then the process starts:

1. Cross bridge formation: utilising the energy from ATP hydrolysis, the myosin head binds to
the exposed active sites on actin to form a cross bridge.

2. The power stroke: when the actin filaments bind myosin, they towards the centre of the sarcomere.

3. Cross Bridge detachment: the
myosin releases the ADP and Pi and goes back to its relaxed state.

4. Reactivation of the myosin head: myosin head is activated again by the attachment of ATP.