The total number of protein-encoding amino acids is

Options

A. 5
B. 20`
C. 12
D. 18

Answer

To solve the question regarding the total number of protein-encoding amino acids, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Amino Acids**:
- Amino acids are the building blocks of proteins. They are organic compounds that contain both an amino group (-NH2) and a carboxyl group (-COOH).
- There are many types of amino acids, but not all of them are involved in protein synthesis.

2. **Total Number of Amino Acids**:
- In nature, there are around 300 different amino acids that have been identified. However, not all of these are used in protein synthesis.

3. **Protein-Encoding Amino Acids**:
- Out of the total amino acids, only 20 are known as protein-encoding amino acids. These are the amino acids that are directly used to build proteins through the process of translation in cells.

4. **Identifying the Correct Option**:
- Given the options: 5, 20, 12, and 18, we need to identify which one corresponds to the number of protein-encoding amino acids.
- Since we established that there are 20 protein-encoding amino acids, the correct answer is 20.

5. **Conclusion**:
- Therefore, the total number of protein-encoding amino acids is **20**.

### Final Answer:
The total number of protein-encoding amino acids is **20**.

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