Question

Which codons serve as punctuation signals?

Short answer

The initiation codons and the stop codons serve as punctuation signals.

Step-by-step solution

Initiation codon

AUG or sometimes GUG serves as the initiation codon, which helps initiate translation to form a polypeptide chain. There are no gaps between the reading frame of nucleotides in the mRNA. Therefore, the start can be considered as punctuation.

Stop codon

There are three stop codons, also known as non-sense codons: UGA, UAG, and UAA. They don’t code for any amino acid and signals for the termination of protein synthesis. Thus, it can be considered as punctuation, a full stop.