Which pairing correctly matches a translation stage with its defining event?

Which pairing correctly matches a translation stage with its defining event?

• A. Elongation — ribosome binds near the start of the mRNA
• B. Translocation — ribosome binds near the start of the mRNA
• C. Initiation — ribosome binds near the start of the mRNA
• D. Termination — tRNA enters the A site

Answer: (C)

Initiation is the stage where the ribosome first attaches to the mRNA and establishes the reading frame by bringing in the initiator tRNA at the start codon. This binding near the start site sets up the entire translation process, positioning the ribosome so the correct codon sequence is read from the very beginning. Elongation involves adding amino acids as charged tRNAs enter the A site and peptide bonds form in the P site, with the ribosome progressively moving along the mRNA. Translocation is the step after each amino acid addition where the ribosome shifts along the mRNA to the next codon. Termination occurs when a stop codon is encountered and release factors trigger release of the completed polypeptide; a tRNA does not enter the A site during termination.

Initiation is the stage where the ribosome first attaches to the mRNA and establishes the reading frame by bringing in the initiator tRNA at the start codon. This binding near the start site sets up the entire translation process, positioning the ribosome so the correct codon sequence is read from the very beginning.

Elongation involves adding amino acids as charged tRNAs enter the A site and peptide bonds form in the P site, with the ribosome progressively moving along the mRNA. Translocation is the step after each amino acid addition where the ribosome shifts along the mRNA to the next codon. Termination occurs when a stop codon is encountered and release factors trigger release of the completed polypeptide; a tRNA does not enter the A site during termination.