Which of the following best describes the difference between a silent mutation and a missense mutation with regard to protein function?

Which of the following best describes the difference between a silent mutation and a missense mutation with regard to protein function?

• A. A silent mutation changes a codon to the same amino acid and typically has no effect.
• B. A silent mutation changes a codon to a different amino acid.
• C. A missense mutation substitutes a different amino acid, potentially altering protein function.
• D. A silent mutation creates a stop codon.

Answer: (C)

The key idea is how the mutation affects the amino acid sequence and thus the protein's function. A silent mutation is a synonymous change: the DNA codon is altered but still codes for the same amino acid, so the amino acid sequence—and typically the protein's function—remains unchanged. A missense mutation changes the codon to encode a different amino acid, which can alter the protein’s properties, structure, or active site and therefore its function, with effects ranging from negligible to severe. So the difference in impact on function comes down to whether the amino acid sequence is altered. The statement that a silent mutation changes a codon to the same amino acid and typically has no effect best captures this contrast. The other descriptions either mischaracterize silent mutations or describe nonsense (stop-codon) mutations.

The key idea is how the mutation affects the amino acid sequence and thus the protein's function. A silent mutation is a synonymous change: the DNA codon is altered but still codes for the same amino acid, so the amino acid sequence—and typically the protein's function—remains unchanged. A missense mutation changes the codon to encode a different amino acid, which can alter the protein’s properties, structure, or active site and therefore its function, with effects ranging from negligible to severe. So the difference in impact on function comes down to whether the amino acid sequence is altered. The statement that a silent mutation changes a codon to the same amino acid and typically has no effect best captures this contrast. The other descriptions either mischaracterize silent mutations or describe nonsense (stop-codon) mutations.