Type of bonds seen in primary structure of proteins

Options

A. Peptide bonds
B. Hydrogen bonds
C. Disulphide bridges
D. All the above

Answer

### Step-by-Step Solution:

1. **Understanding Proteins**:
- Proteins are large biomolecules made up of chains of amino acids. The sequence of these amino acids determines the protein's structure and function.

2. **Identifying the Primary Structure**:
- The primary structure of a protein refers to the specific sequence of amino acids linked together in a linear chain. This sequence is crucial as it dictates how the protein will fold and function.

3. **Types of Bonds in Primary Structure**:
- The main type of bond that forms between amino acids in the primary structure is the **peptide bond**. This bond is formed through a dehydration synthesis reaction where the carboxyl group of one amino acid reacts with the amino group of another, releasing a molecule of water.

4. **Other Bonds**:
- While hydrogen bonds and disulfide bonds are important in the secondary and tertiary structures of proteins, they do not play a role in the primary structure.
- Hydrogen bonds help stabilize the secondary structure (like alpha-helices and beta-sheets), and disulfide bonds (covalent bonds between sulfur atoms in cysteine residues) contribute to the tertiary structure.

5. **Conclusion**:
- Therefore, the only bond that is seen in the primary structure of proteins is the peptide bond. The correct answer to the question is **Option A: Peptide bond**.