Acidic amino acids have two-COOH groups and one `-NH_(2)` group per molecule. Select the pair that consists of acidic amino acids.

Options

A. Aspartic acid, glutamic acid
B. Lysine, arginine
C. Glycine, alanine
D. Both (a) and (b)

Explanation

To solve the question of identifying the pair that consists of acidic amino acids, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Definition of Acidic Amino Acids**:
Acidic amino acids are defined as having two carboxylic acid groups (-COOH) and one amino group (-NH2) in their structure.

2. **Identify the General Structure of Amino Acids**:
All amino acids have a central alpha carbon connected to:
- An amino group (-NH2)
- A hydrogen atom
- A carboxylic acid group (-COOH)
- A variable side chain (R group)

3. **Analyze the Given Options**:
We need to check the structures of the amino acids in each option to see if they meet the criteria for being acidic.

4. **Option A: Aspartic Acid and Glutamic Acid**:
- **Aspartic Acid**: Contains one carboxylic acid group from the backbone and one from the side chain (total of 2 -COOH).
- **Glutamic Acid**: Similar to aspartic acid, it has one carboxylic acid group from the backbone and one from the side chain (total of 2 -COOH).
- Both these amino acids satisfy the condition of having two -COOH groups and one -NH2 group.

5. **Option B: Lysine and Arginine**:
- **Lysine**: Contains one -COOH group and two -NH2 groups (one in the backbone and one in the side chain).
- **Arginine**: Also contains one -COOH group and three -NH2 groups.
- Neither of these amino acids is acidic as they do not have two -COOH groups.

6. **Option C: Glycine and Alanine**:
- **Glycine**: Contains one -COOH group and one -NH2 group.
- **Alanine**: Similar to glycine, it has one -COOH group and one -NH2 group.
- Both are neutral amino acids and do not meet the criteria for acidic amino acids.

7. **Conclusion**:
Based on the analysis, the only pair that consists of acidic amino acids is **Option A: Aspartic Acid and Glutamic Acid**.

### Final Answer:
The pair that consists of acidic amino acids is **Aspartic Acid and Glutamic Acid**.

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