In the protein synthesis, tRNA carrying the amino acid enters from which site of ribosome?

Options

A. A' site
B. P' site
C. anticodo site
D. recognition site

Answer

**Step-by-Step Solution:**

1. **Understanding Protein Synthesis**: The process of protein synthesis involves two main stages: transcription and translation. In this context, we are focusing on translation, where the mRNA is translated into a protein.

2. **Role of Ribosomes**: Ribosomes are essential for protein synthesis and are often referred to as the "protein factory" of the cell. They consist of two subunits: a small subunit and a large subunit.

3. **tRNA Function**: Transfer RNA (tRNA) is responsible for bringing amino acids to the ribosome during translation. Each tRNA molecule has an anticodon that pairs with the corresponding codon on the mRNA.

4. **Ribosome Sites**: The ribosome has three key sites where tRNA can bind:
- **A site (Aminoacyl site)**: This is where the tRNA carrying the next amino acid enters the ribosome.
- **P site (Peptidyl site)**: This site holds the tRNA that is currently attached to the growing polypeptide chain.
- **E site (Exit site)**: This is where the tRNA exits the ribosome after its amino acid has been added to the chain.

5. **Entry of tRNA**: The tRNA carrying the amino acid enters the ribosome specifically at the A site. This is the first point of contact for the tRNA during the translation process.

6. **Process of Amino Acid Transfer**: Once the tRNA is in the A site, the amino acid it carries is transferred to the growing polypeptide chain held by the tRNA in the P site. After this transfer, the tRNA in the P site moves to the E site to exit the ribosome.

7. **Conclusion**: Therefore, the tRNA carrying the amino acid enters the ribosome from the A site.

**Final Answer**: The tRNA carrying the amino acid enters the ribosome from the A site.

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