If a codon changes to a stop codon, it is

If a codon changes to a stop codon, it is

• A. Missense mutation
• B. Nonsense mutation
• C. Silent mutation
• D. Frameshift mutation

Answer: (B)

When a codon is changed into a stop codon, translation ends early and the protein is shortened. This specific change is called a nonsense mutation. The ribosome stops where the new stop codon appears, so most of the normal protein never gets made. A missense mutation would replace one amino acid with another but keep translation going. A silent mutation would still code for the same amino acid, so the protein sequence remains unchanged. A frameshift mutation arises from insertions or deletions that shift the reading frame, usually altering many downstream amino acids and often creating a premature stop, but the defining feature here is the direct conversion to a stop codon, which is the hallmark of a nonsense mutation.

When a codon is changed into a stop codon, translation ends early and the protein is shortened. This specific change is called a nonsense mutation. The ribosome stops where the new stop codon appears, so most of the normal protein never gets made. A missense mutation would replace one amino acid with another but keep translation going. A silent mutation would still code for the same amino acid, so the protein sequence remains unchanged. A frameshift mutation arises from insertions or deletions that shift the reading frame, usually altering many downstream amino acids and often creating a premature stop, but the defining feature here is the direct conversion to a stop codon, which is the hallmark of a nonsense mutation.