Which mutation type replaces one amino acid with another?

Which mutation type replaces one amino acid with another?

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

Answer: (B)

A missense mutation is a single nucleotide change that alters a codon so it specifies a different amino acid. That substitution changes one amino acid in the protein sequence, which is exactly what this question describes. Other mutation types do different things: a nonsense mutation creates a premature stop codon and truncates the protein; a silent mutation changes the DNA but still encodes the same amino acid, leaving the protein sequence unchanged; a frameshift mutation results from insertions or deletions that shift the reading frame, altering many downstream amino acids. Because the key effect here is substituting one amino acid for another, the missense mutation best fits.

A missense mutation is a single nucleotide change that alters a codon so it specifies a different amino acid. That substitution changes one amino acid in the protein sequence, which is exactly what this question describes. Other mutation types do different things: a nonsense mutation creates a premature stop codon and truncates the protein; a silent mutation changes the DNA but still encodes the same amino acid, leaving the protein sequence unchanged; a frameshift mutation results from insertions or deletions that shift the reading frame, altering many downstream amino acids. Because the key effect here is substituting one amino acid for another, the missense mutation best fits.