Question

The process consists of the myosin head binding to actin and pulling it forward in an action known as:

A) Cross-bridging

B) Myosin-actin coupling

C) Tropomyosin binding

D) Sarcomere contraction

Answer 1

The process of the myosin head binding to actin and pulling it forward, leading to muscle contraction, is known as cross-bridging.

Step-by-step explanation:

The process consists of the myosin head binding to actin and pulling it forward in an action known as cross-bridging. This process involves several steps critical to muscle contraction:

1. Myosin binds to an actin filament while ADP and Pi are bound to the myosin head, forming a cross-bridge.
2. A power stroke occurs, moving the actin filament inward toward the sarcomere center and shortening the sarcomere.
3. ADP and Pi are released, and ATP binds to the myosin head, leading to the detachment of the myosin from the actin.
4. ATP is hydrolyzed, re-cocking the myosin head into a position ready for another cycle.

This cyclical process, referred to as the cross-bridge cycle, is vital for the contraction of muscles and is powered by ATP. Each myosin head operates like an oar in a rowing action, requiring ATP for each cycle to continue moving the actin filaments, and thus, contracting the muscle.