Which mutation type changes a codon to code for a different amino acid?

Which mutation type changes a codon to code for a different amino acid?

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

Answer: (A)

A missense mutation. It happens when a single nucleotide change alters a codon so that it encodes a different amino acid, changing the protein sequence downstream of the mutation. The genetic code is redundant for many amino acids, so not all substitutions change the amino acid (these are silent), but when the codon now specifies a different amino acid, the protein’s properties can be affected. In contrast, a nonsense mutation creates a stop codon and truncates the protein, a silent mutation leaves the same amino acid in place due to codon redundancy, and a frameshift mutation shifts the reading frame by insertions or deletions, altering many downstream amino acids.

A missense mutation. It happens when a single nucleotide change alters a codon so that it encodes a different amino acid, changing the protein sequence downstream of the mutation. The genetic code is redundant for many amino acids, so not all substitutions change the amino acid (these are silent), but when the codon now specifies a different amino acid, the protein’s properties can be affected. In contrast, a nonsense mutation creates a stop codon and truncates the protein, a silent mutation leaves the same amino acid in place due to codon redundancy, and a frameshift mutation shifts the reading frame by insertions or deletions, altering many downstream amino acids.