Genetic code terminology: Codons that do not specify any amino acid are called what in molecular genetics?

Introduction / Context:
The genetic code includes sense codons (coding for amino acids) and nonsense codons that signal the end of translation. Recognizing stop codons is critical for interpreting open reading frames and designing expression constructs.

Given Data / Assumptions:

• Nonsense/stop codons are UAA, UAG, and UGA.
• They do not encode an amino acid but recruit release factors.
• Question asks for the correct term describing such codons.

Concept / Approach:
“Termination codons” or “stop codons” halt elongation by promoting peptide release from the ribosome. “Initiation” refers to start, not stop, and “propagation” is not standard terminology in the code.

Step-by-Step Solution:

Verification / Alternative check:
Genome annotation pipelines define ORFs from start to the first in-frame stop codon, confirming usage of the term.

Why Other Options Are Wrong:

• Initiation codons: AUG (and rarely GUG/UUG) mark start, not stop.
• Propagation codons: not a standard term in genetics.
• None: incorrect because a standard term exists.

Common Pitfalls:
Confusing “nonsense mutation” (creating a stop codon) with missense/silent changes; ensure terminology is precise.

Final Answer:
Termination codons (stop codons)