Where is amino acid added during elongation?

Where is amino acid added during elongation?

• A. To the carboxyl site
• B. To the amino site
• C. To the tRNA binding site
• D. To the exit tunnel

Answer: (A)

During elongation, amino acids are added to the carboxyl end (C-terminus) of the growing polypeptide. The incoming aminoacyl-tRNA brings its amino acid to the ribosome and forms a peptide bond with the carboxyl end of the chain attached to the tRNA in the previous site. This bond formation extends the chain, placing the new amino acid at the chain’s carboxyl terminus. After this, the ribosome shifts to make room for the next aminoacyl-tRNA. The exit tunnel simply serves as the path for the finished polypeptide to leave, not where additions occur.

During elongation, amino acids are added to the carboxyl end (C-terminus) of the growing polypeptide. The incoming aminoacyl-tRNA brings its amino acid to the ribosome and forms a peptide bond with the carboxyl end of the chain attached to the tRNA in the previous site. This bond formation extends the chain, placing the new amino acid at the chain’s carboxyl terminus. After this, the ribosome shifts to make room for the next aminoacyl-tRNA. The exit tunnel simply serves as the path for the finished polypeptide to leave, not where additions occur.