Question

question 6
1 pts
muscle contraction is caused by
sarcomeres moving along other sarcomeres.
contraction of actin and myosin filaments.
movement of bones that anchor the muscles.
myosin filaments sliding along actin filaments.

Explanation:

Muscle contraction is explained by the sliding - filament theory. Sarcomeres are the basic units of muscle contraction. Actin and myosin filaments are within the sarcomere. Actin filaments are thin, and myosin filaments are thick. During contraction, myosin heads bind to actin (forming cross - bridges), and then undergo a power stroke that pulls the actin filaments towards the center of the sarcomere. This is a sliding motion of myosin filaments along actin filaments. Actin and myosin filaments themselves do not contract in length (they are just sliding past each other). Sarcomeres do not move along other sarcomeres in the way described in the first option. The movement of bones (which is the result of muscle contraction, via the pull on tendons attached to bones) is not the cause of muscle contraction itself.

Answer:

myosin filaments sliding along actin filaments.