Formation of a peptide bond involves

Options

A. Two amino acids
B. Two monosaccharides
C. A condensation reaction
D. Both A and C.

Answer

### Step-by-Step Solution:

1. **Understanding Peptide Bonds**: A peptide bond is a specific type of covalent bond that links amino acids together in a protein. It is formed during the process of protein synthesis.

2. **Components Involved**: The formation of a peptide bond involves two amino acids. Each amino acid has an amino group (-NH2), a carboxyl group (-COOH), and a variable side chain (R group).

3. **Condensation Reaction**: The formation of a peptide bond is a type of condensation reaction. In this reaction, two molecules (in this case, amino acids) combine to form a larger molecule (a dipeptide) while releasing a small molecule, typically water (H2O).

4. **Mechanism of Peptide Bond Formation**:
- When two amino acids come together, the carboxyl group of one amino acid reacts with the amino group of the other.
- This reaction results in the release of a water molecule (H2O) and the formation of a peptide bond (-CO-NH-).

5. **Conclusion**: Therefore, the correct answer to the question "Formation of a peptide bond involves" is:
- **A**: 2 amino acids
- **C**: A condensation reaction
- Thus, the correct option is **D**: Both A and C.