An `alpha` helix is the example of which level of protein structure?

Options

A. `1^(@)`
B. `2^(@)`
C. `3^(@)`
D. `4^(@)`

Answer

To determine the level of protein structure represented by an alpha helix, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Protein Structure**: Proteins have four levels of structure: primary, secondary, tertiary, and quaternary. Each level represents a different aspect of the protein's formation and organization.

2. **Identifying the Building Blocks**: Proteins are polymers made up of smaller units called amino acids. These amino acids are linked together by peptide bonds to form a polypeptide chain.

3. **Recognizing the Primary Structure**: The primary structure of a protein refers to the linear sequence of amino acids in the polypeptide chain. This is the most basic level of protein structure.

4. **Defining Secondary Structure**: The secondary structure of a protein refers to the local folded structures that form within a polypeptide due to interactions between the backbone atoms. Common types of secondary structures include alpha helices and beta-pleated sheets.

5. **Identifying Alpha Helix**: An alpha helix is a specific type of secondary structure characterized by a right-handed coil where each turn of the helix is stabilized by hydrogen bonds between the backbone atoms.

6. **Conclusion**: Since the alpha helix is a type of local folding that occurs in the polypeptide chain, it is classified as a secondary structure of protein.

### Final Answer:
An alpha helix is an example of the **secondary level of protein structure**.

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