Light bands of muscle fiber consist of filaments called____whereas dark bands consist of filaments called_____

Answer

**Step-by-Step Text Solution:**

1. **Understanding Muscle Fiber Structure**: Muscle fibers are composed of two main types of protein filaments that are crucial for muscle contraction and relaxation. These proteins are actin and myosin.

2. **Identifying Light Bands**: The light bands in muscle fibers are primarily made up of actin filaments. Actin is a relatively thin protein filament, and when stained, it produces a light color, which corresponds to the light bands.

3. **Identifying Dark Bands**: The dark bands in muscle fibers consist of myosin filaments. Myosin is thicker than actin, and when stained, it produces a darker color, corresponding to the dark bands.

4. **Naming the Bands**: The light bands are referred to as I bands (isotropic bands), while the dark bands are called A bands (anisotropic bands).

5. **Final Answer**: Therefore, the light bands of muscle fiber consist of filaments called **actin**, whereas the dark bands consist of filaments called **myosin**.

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