Peptide bond is a key feature in:

Options

A. Polysaccharide
B. Proteins
C. Nucleotide
D. Vitamins

Answer

To solve the question "Peptide bond is a key feature in:", we need to analyze the options provided: polysaccharide, proteins, nucleotides, and vitamins.

### Step-by-Step Solution:

1. **Understanding Peptide Bonds**:
- A peptide bond is a type of covalent bond that links amino acids together in proteins. It is formed through a condensation reaction where the carboxyl group of one amino acid reacts with the amino group of another, releasing a molecule of water.

2. **Analyzing the Options**:
- **Polysaccharides**: These are carbohydrates made up of sugar units linked by glycosidic bonds, not peptide bonds. Examples include starch and cellulose.
- **Proteins**: Proteins are polymers made up of amino acids linked by peptide bonds. This is the correct answer.
- **Nucleotides**: Nucleotides are the building blocks of nucleic acids (DNA and RNA) and are linked by phosphodiester bonds, not peptide bonds.
- **Vitamins**: Vitamins are organic compounds that are essential in small amounts for various biochemical functions. They do not contain peptide bonds.

3. **Conclusion**:
- Since peptide bonds are specifically associated with proteins, the correct answer to the question is **proteins**.

### Final Answer:
Peptide bond is a key feature in **proteins**.

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