Questions: Which of the following is predominately made up of myosin? G actin Factin The thin filament The thick filament The elastic filament

The answer is the fourth one: The thick filament.

Explanation for each option:

1. G actin: This is a globular protein that polymerizes to form F actin, which is a major component of the thin filament in muscle fibers. It is not made up of myosin.

2. F actin: This is a filamentous protein formed by the polymerization of G actin. It is a key component of the thin filament, not the thick filament, and does not contain myosin.

3. The thin filament: This filament is primarily composed of actin, along with regulatory proteins like tropomyosin and troponin. It is not made up of myosin.

4. The thick filament: This filament is predominantly made up of myosin molecules. Myosin is a motor protein that interacts with actin to facilitate muscle contraction.

5. The elastic filament: This filament is primarily composed of the protein titin, which helps maintain the structure of the sarcomere and provides elasticity. It is not made up of myosin.

In summary, the thick filament is the structure that is predominantly made up of myosin.