Question

When calcium ions are released into muscle fibers, what happens along the actin filament? Multiple Choice The position of the tropomyosin threads shift, hiding myosin binding sites, causing the myosin head to move farther away from the actin filament. The position of the tropomyosin threads shift, exposing myosin binding sites, allowing the myosin head to attach to the actin filament. The position of the actin filaments shift, exposing myosin binding sites, causing the myosin head to move farther away from the tropomyosin threads. The position of the actin filaments shift, hiding myosin binding sites, allowing the myosin head to attach to the tropomyosin threads.

Answer 1

Answer:

The correct answer will be options

1. The position of the tropomyosin threads shift

2. Exposing myosin binding sites

3. Allowing the myosin head to attach to the actin filament

Explanation:

Calcium plays an important role in the contraction of muscles especially in the formation of the cross-bridge between myosin and actin filaments.

In the presence of calcium, myosin head binds the actin filament as calcium binds to the troponin which changes the configuration of the troponin which releases the tropomyosin from the myosin-binding site on actin.

Once the myosin binding site is freed, myosin binds the site and causes muscle contraction due to ATP hydrolysis.

Thus, the selected options are the correct answer.