What determines how nucleotides are grouped into codons during translation?

What determines how nucleotides are grouped into codons during translation?

• A. Reading frame
• B. Promoter sequence
• C. Splice site
• D. Ribosome binding site

Answer: (A)

Codons are read in fixed three-nucleotide chunks, and the starting point for that grouping—the reading frame—determines which nucleotides make up each codon. The ribosome begins translation at a start codon and then maintains that frame as it moves along the mRNA; shifting the frame changes every downstream codon and the resulting amino acid sequence. This is why the reading frame is essential for correct protein synthesis. The promoter sequence relates to transcription initiation, not translation; splice sites govern RNA processing; and although a ribosome binding site helps recruit the ribosome, it does not set the three-nucleotide grouping once translation has started.

Codons are read in fixed three-nucleotide chunks, and the starting point for that grouping—the reading frame—determines which nucleotides make up each codon. The ribosome begins translation at a start codon and then maintains that frame as it moves along the mRNA; shifting the frame changes every downstream codon and the resulting amino acid sequence. This is why the reading frame is essential for correct protein synthesis. The promoter sequence relates to transcription initiation, not translation; splice sites govern RNA processing; and although a ribosome binding site helps recruit the ribosome, it does not set the three-nucleotide grouping once translation has started.