Question

what must occur for protein translation to begin?
a water molecule must be added to the protein chain.
a peptide bond must form between subunits of mrna.
the amino acid cys must be picked up by trna.
the codon aug must be identified.

Explanation:

• Option 1: Adding a water molecule is part of peptide bond hydrolysis (not initiation), so incorrect.
• Option 2: Peptide bonds form between amino acids (not mRNA subunits) during elongation, incorrect.
• Option 3: Initiation doesn’t require Cys specifically; AUG codes for Met (start codon), incorrect.
• Option 4: Translation initiation requires the ribosome to identify the start codon AUG (codes for methionine), which signals the start of protein synthesis. Correct.

Answer:

D. The codon AUG must be identified.