The amino acid found only in bacterial and blue - green algae is

Options

A. methionine
B. diamino - pimelic acid
C. aspartic acid
D. glutamic acid

Answer

To solve the question regarding the amino acid found only in bacteria and blue-green algae, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Options**: The question provides several amino acids as options. We need to analyze each option to determine if it is exclusive to bacteria and blue-green algae.

2. **Evaluate Methionine**:
- Methionine is a standard amino acid that is found in all living cells, including plants, animals, and bacteria. Therefore, it cannot be the answer.

3. **Evaluate Aspartic Acid and Glutamic Acid**:
- Both aspartic acid and glutamic acid are common amino acids that are present in all organisms. They are not exclusive to bacteria or blue-green algae, so they can be eliminated as options.

4. **Evaluate Diaminopimelic Acid**:
- Diaminopimelic acid (DAP) is a derivative of lysine. It plays a crucial role in the formation of peptidoglycan, which is a major component of the bacterial cell wall. Peptidoglycan is also found in blue-green algae (cyanobacteria).
- Since DAP is specifically involved in the structure of the cell wall in these organisms, it is indeed exclusive to bacteria and blue-green algae.

5. **Conclusion**:
- Based on the analysis, the amino acid that is found only in bacteria and blue-green algae is **diaminopimelic acid**.

### Final Answer:
The amino acid found only in bacterial and blue-green algae is **diaminopimelic acid**.