Structural proteins are usually

Options

A. fibrous
B. globular
C. enzymatic
D. soluble

Answer

**Step-by-Step Solution:**

1. **Understanding Structural Proteins**: Structural proteins are proteins that play a critical role in providing support and shape to cells and tissues in an organism. They are essential for the integrity of various structures within the body.

2. **Characteristics of Structural Proteins**: These proteins are typically fibrous in nature. This means they are composed of long, thread-like molecules that can form fibers. This fibrous structure allows them to provide mechanical support.

3. **Role of Structural Proteins**: The primary function of structural proteins is to provide mechanical support to cells and tissues. They help maintain the shape of cells and are crucial for the overall architecture of tissues.

4. **Location of Structural Proteins**: Structural proteins are predominantly found in connective tissues, such as cartilage and bones. These tissues require strong structural components to maintain their form and function.

5. **Examples of Structural Proteins**:
- **Keratin**: Found in hair, nails, and the outer layer of skin, providing protection and structure.
- **Collagen**: The most abundant protein in the body, found in skin, bones, and connective tissues, providing strength and support.
- **Elastin**: Provides elasticity to tissues, allowing them to stretch and return to their original shape.

6. **Conclusion**: Based on the characteristics and roles of structural proteins, they are classified as fibrous proteins.

**Final Answer**: Structural proteins are usually fibrous.

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