During translation, where is the tRNA that is attached to the growing polypeptide chain located?

• A. Cytoplasm
• B. E site of the ribosome
• C. A site of the ribosome
• D. P site of the ribosome

Answer: (D)

Verified step by step guidance

1. Understand the process of translation, which is the synthesis of proteins from mRNA templates. This occurs in the ribosome, a complex molecular machine found within all living cells.
2. Recognize that tRNA (transfer RNA) molecules play a crucial role in translation by bringing amino acids to the ribosome, where they are added to the growing polypeptide chain.
3. Identify the three sites on the ribosome where tRNA molecules bind during translation: the A site (aminoacyl site), the P site (peptidyl site), and the E site (exit site).
4. Know that the tRNA carrying the growing polypeptide chain is located at the P site of the ribosome. This is where the peptide bond formation occurs, linking the new amino acid to the chain.
5. Remember that after the peptide bond is formed, the ribosome shifts, moving the tRNA from the A site to the P site, and the tRNA that was in the P site moves to the E site to exit the ribosome.