Which set lists the steps in protein synthesis?

• A. Transcription
• B. Translation
• C. Replication
• D. Initiation, Elongation, Termination

Answer: (D)

Protein synthesis proceeds through a cycle that occurs during translation: initiation, elongation, and termination. During initiation, the ribosome assembles at the start codon on the mRNA with the initiator tRNA bringing the first amino acid. In elongation, amino acids are added one by one as tRNAs recognize successive codons and peptide bonds form between amino acids. Termination happens when a stop codon is reached; release factors help release the completed polypeptide and the ribosome disassembles. This sequence describes the actual steps by which a protein is built from mRNA. Transcription is the preceding step that converts DNA to RNA, and replication is DNA duplication, not part of the protein-building steps.