Choose Correct statements about proteins

Options

A. Primary structure of proteins refer to amino acid sequence
B. Interaction between three polypeptide chains give rise to tertiary structure of proteins
C. Association between four polypeptide chains give quaternary structure of proteins
D. Folding of polypeptide chain due to interaction between carbonyl group and `-overset(|)N-H` group of peptide linkage give rise to secondry structure

Answer

To solve the question "Choose Correct statements about proteins," we need to evaluate each of the provided statements regarding proteins and determine which ones are correct.

### Step-by-Step Solution:

1. **Evaluate Statement A**:
- **Statement**: "Primary structure of proteins refers to amino acid sequence."
- **Analysis**: The primary structure of a protein is indeed defined as the specific sequence of amino acids linked together by peptide bonds. This sequence determines the protein's unique characteristics and function.
- **Conclusion**: **Correct**.

2. **Evaluate Statement B**:
- **Statement**: "Interaction between three polypeptide chains give rise to tertiary structure of proteins."
- **Analysis**: The tertiary structure of proteins is formed by the folding of a single polypeptide chain into a three-dimensional shape. It is not correct to say that three polypeptide chains together create the tertiary structure; rather, it's the interactions within one polypeptide chain that lead to its tertiary structure.
- **Conclusion**: **Incorrect**.

3. **Evaluate Statement C**:
- **Statement**: "Association between four polypeptide chains give quaternary structure of proteins."
- **Analysis**: The quaternary structure refers to the arrangement of multiple polypeptide chains (subunits) in a protein. However, it is not limited to just four polypeptide chains; it can involve any number of chains. Therefore, this statement is misleading.
- **Conclusion**: **Incorrect**.

4. **Evaluate Statement D**:
- **Statement**: "Folding of polypeptide chain due to interaction between carbonyl group and NH group of peptide linkage give rise to secondary structure."
- **Analysis**: The secondary structure of proteins, such as alpha helices and beta sheets, is stabilized by hydrogen bonds formed between the carbonyl (C=O) of one amino acid and the amide (NH) of another. This statement accurately describes the formation of secondary structures.
- **Conclusion**: **Correct**.

### Final Answer:
The correct statements about proteins are:
- **A**: Primary structure of proteins refers to amino acid sequence.
- **D**: Folding of polypeptide chain due to interaction between carbonyl group and NH group of peptide linkage give rise to secondary structure.