Explain the role of transfer RNA (tRNA) in translation.

IB DP Biology Standard Level (2023 syllabus) — D1.2 Protein synthesis · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

tRNA carries a specific amino acid to the ribosome
The anticodon of tRNA is complementary to the codon on mRNA, ensuring the correct amino acid is added in the correct sequence
A peptide bond forms between adjacent amino acids; the tRNA then releases its amino acid and the uncharged tRNA leaves the ribosome

Examiner tips

Use the term ‘anticodon’ and ‘codon’ explicitly
Show the sequence of events: amino acid transfer, peptide bond, tRNA release
Mention the ribosome as the site of translation
Keep the answer concise and focused on the four key points

Common mistakes

Confusing tRNA with rRNA or mRNA
Omitting the anticodon–codon complementarity
Failing to mention the peptide bond formation

Mark scheme (4 marks)

tRNA carries/transports a specific amino acid to the ribosome
The anticodon of tRNA is complementary to/base-pairs with the codon on mRNA
This ensures the correct/specific amino acid is added in the correct sequence/order
A peptide bond forms between adjacent amino acids / tRNA releases its amino acid once the peptide bond is formed, and the (uncharged) tRNA leaves the ribosome

Key terms in this question

transfer RNA (tRNA) · translation