An acidic amino acid has an alkyl R chain containing an extra

Options

A. `-COOH` group
B. `-NH_(2)` group
C. `-OH` group
D. `-CH_(2)` group.

Answer

To solve the question regarding the structure of an acidic amino acid with an alkyl R chain containing an extra group, we can follow these steps:

### Step-by-Step Solution:

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

2. **Identifying Acidic Amino Acids**:
- Acidic amino acids are characterized by having an extra carboxyl group in their side chain (R group). The two main acidic amino acids are aspartic acid (aspartate) and glutamic acid (glutamate).

3. **Analyzing the R Chain**:
- The question specifies that the acidic amino acid has an alkyl R chain containing an extra group. For acidic amino acids, this extra group is typically another carboxylic acid (-COOH).

4. **Conclusion**:
- Therefore, the correct answer to the question is that an acidic amino acid has an alkyl R chain containing an extra **carboxylic group**.

### Final Answer:
The correct option is **carboxylic group**.

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