Which one of the following is a basic amino acid ?

Options

A. `{:(" "COOH),(" "|),(H_(2)N-C-H),(" "|),(" "CH(CH_(3))_(2)):}`
B. `{:(" "COO H),(" "|),(H_(2)N-C-H),(" "|),(" "(CH_(2))_(4)NH_(2)):}`
C. `{:(" "COO H),(" "|),(H_(2)N-C-H),(" "|),(" "CH_(2)OH):}`
D. `{:(" "COO H),(" "|),(H_(2)N-C-H),(" "|),(" "CH_(3)):}`

Answer

To determine which one of the following is a basic amino acid, we need to follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure of Amino Acids**:
- Amino acids have a central carbon atom (chiral carbon) attached to four different groups: an amino group (-NH2), a carboxylic acid group (-COOH), a hydrogen atom, and a variable side chain (R group).

2. **Identify Basic Amino Acids**:
- Basic amino acids are characterized by the presence of more than one amino group. The basicity of an amino acid is determined by the number of amino groups it contains.

3. **Analyze the Given Structures**:
- Examine each option provided to identify the number of amino groups present in each structure.

4. **Evaluate Each Option**:
- **Option 1**: Contains only one amino group. Not a basic amino acid.
- **Option 2**: Contains two amino groups (one main and one in the functional group). This is a basic amino acid.
- **Option 3**: Contains only one amino group. Not a basic amino acid.
- **Option 4**: Contains only one amino group. Not a basic amino acid.

5. **Select the Correct Answer**:
- Based on the analysis, the correct answer is **Option 2**, as it is the only structure that contains two amino groups.

### Final Answer:
The basic amino acid among the options is **Option 2**.

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