There are many types of amino acids on the basis of -

Options

A. `NH_(2)` group
B. COOH group
C. R group
D. None

Answer

### Step-by-Step Solution

1. **Understanding the Structure of Amino Acids**:
- Amino acids are organic compounds that serve as the building blocks of proteins. Each amino acid has a central carbon atom bonded to four different groups: a carboxyl group (-COOH), an amino group (-NH2), a hydrogen atom (H), and a variable side chain known as the R group.

2. **Identifying the Components**:
- The general structure of an amino acid can be represented as:
- Central Carbon (C)
- Carboxyl Group (–COOH)
- Amino Group (–NH2)
- Hydrogen Atom (H)
- R Group (Variable Side Chain)

3. **Recognizing the Importance of the R Group**:
- The R group is what differentiates one amino acid from another. While the carboxyl group, amino group, and hydrogen atom remain constant across all amino acids, the R group varies, leading to the diversity of amino acids.

4. **Examples of Amino Acids**:
- For instance, in glycine, the R group is simply a hydrogen atom (H), making its structure:
- NH2-CH(Glycine)-COOH
- In alanine, the R group is a methyl group (–CH3), leading to its structure:
- NH2-CH(CH3)-COOH

5. **Conclusion**:
- Therefore, amino acids can be classified into different types based on the nature of their R group. This classification is crucial for understanding the functional diversity of proteins.

### Final Answer:
Amino acids are classified into many types based on their R group.

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