The structure formed by the sequence of amino acids in a polypeptide chain is called :

Options

A. primary
B. secondary
C. tertiary
D. quaternary

Explanation

To answer the question, "The structure formed by the sequence of amino acids in a polypeptide chain is called:", we can break down the solution into the following steps:

### Step-by-Step Solution:

1. **Understanding Polypeptides and Proteins**:
- A polypeptide is a chain of amino acids linked together by peptide bonds. When many amino acids are joined together, they form a protein.

2. **Defining the Structure**:
- The sequence of amino acids in a polypeptide chain determines the specific structure of the protein. This sequence is crucial because it dictates how the protein will fold and function.

3. **Identifying the Types of Protein Structures**:
- Proteins have four levels of structure:
- **Primary Structure**: The linear sequence of amino acids.
- **Secondary Structure**: Local folding into structures like alpha helices and beta sheets.
- **Tertiary Structure**: The overall 3D shape of a single polypeptide chain.
- **Quaternary Structure**: The arrangement of multiple polypeptide chains into a functional protein.

4. **Determining the Correct Answer**:
- The question specifically asks for the structure formed by the sequence of amino acids. This is defined as the **primary structure** of the protein.

5. **Conclusion**:
- Therefore, the correct answer to the question is that the structure formed by the sequence of amino acids in a polypeptide chain is called the **primary structure**.

### Final Answer:
The structure formed by the sequence of amino acids in a polypeptide chain is called the **primary structure**.

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