A basic amino acid among the following is

Options

A. glycine
B. valine
C. proline
D. histidine

Answer

To determine which amino acid among the given options is a basic amino acid, we need to analyze the structure of each amino acid and count the number of basic (amino) groups and acidic (carboxyl) groups present.

### Step-by-Step Solution:

1. **Understanding Amino Acids**:
- An amino acid generally has one amino group (-NH2) and one carboxyl group (-COOH). The amino group is basic, while the carboxyl group is acidic.

2. **Identifying Basic Amino Acids**:
- A basic amino acid has more basic groups than acidic groups. This means we need to find an amino acid that has more than one amino group or additional nitrogen atoms that contribute to basicity.

3. **Analyzing the Given Options**:
- **Option 1: Glycine (NH2-CH2-COOH)**:
- Contains 1 amino group and 1 carboxyl group.
- Basic groups = 1, Acidic groups = 1.
- This does not qualify as a basic amino acid.

- **Option 2: Valine (NH2-CH(CH3)2-COOH)**:
- Contains 1 amino group and 1 carboxyl group.
- Basic groups = 1, Acidic groups = 1.
- This does not qualify as a basic amino acid.

- **Option 3: Proline (C5H9NO2)**:
- Contains 1 amino group and 1 carboxyl group.
- Basic groups = 1, Acidic groups = 1.
- This does not qualify as a basic amino acid.

- **Option 4: Histidine (C6H9N3O2)**:
- Contains 3 nitrogen atoms (2 in the imidazole ring and 1 in the amino group) and 1 carboxyl group.
- Basic groups = 3, Acidic groups = 1.
- This qualifies as a basic amino acid because it has more basic groups than acidic groups.

4. **Conclusion**:
- The basic amino acid among the given options is **Histidine** (Option 4).