Basic unit of muscle contraction is

Options

A. Actin
B. Myosin
C. Sarcomere
D. Tropomyosin.

Answer

**Step-by-Step Solution:**

1. **Understanding Muscle Structure**: Muscles are made up of fibers that contain contractile proteins, primarily actin and myosin. These proteins are arranged in a specific manner that allows for contraction.

2. **Identifying Contractile Proteins**: Myosin forms the thick filaments and is responsible for the dark bands (A-band) in muscle tissue, while actin forms the thin filaments and is responsible for the light bands (I-band).

3. **Defining the Sarcomere**: The basic unit of muscle contraction is called the sarcomere. A sarcomere is defined as the segment of muscle fiber that lies between two Z-discs (or Z-lines).

4. **Function During Contraction**: During muscle contraction, the sarcomere shortens as the actin and myosin filaments slide past each other. The lengths of the filaments remain unchanged, but the Z-discs move closer together, resulting in the contraction of the muscle.

5. **Conclusion**: Therefore, the basic unit of muscle contraction is the sarcomere.

**Final Answer**: The basic unit of muscle contraction is the **sarcomere**.

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