How many amino acids are used in protein synthesis?

Answer

### Step-by-Step Solution

1. **Understanding Amino Acids**:
- Amino acids are organic compounds that serve as the building blocks of proteins. They play a crucial role in various biological processes.

2. **Function of Amino Acids**:
- The primary function of amino acids is to act as monomer units in protein synthesis. They can also serve as substrates for biochemical reactions and are involved in the formation of nucleotides, hormones, and neurotransmitters.

3. **Defining Translation**:
- Translation is the process through which proteins are synthesized from the genetic code carried by mRNA. It is a key step in protein synthesis.

4. **Number of Amino Acids in Nature**:
- Scientists have identified more than 500 different amino acids in nature. However, not all of these are involved in protein synthesis.

5. **Amino Acids Used in Protein Synthesis**:
- Out of the total amino acids, only 22 are utilized in the process of translation (protein synthesis). This includes 20 common amino acids and 2 additional ones: selenocysteine and pyrrolysine.

6. **Final Answer**:
- Therefore, the total number of amino acids used in protein synthesis is **22**.