Which of the following describes a mutation that does not affect the amino acid sequence of a protein?

Which of the following describes a mutation that does not affect the amino acid sequence of a protein?

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

Answer: (B)

A silent mutation is characterized by a change in the DNA sequence that does not alter the amino acid sequence of the resulting protein. This occurs due to the redundancy in the genetic code, where multiple codons can code for the same amino acid. For instance, if a nucleotide change occurs but the new codon still codes for the same amino acid, the overall structure and function of the protein remain unchanged. Thus, the silent mutation does not have a phenotypic effect because the protein produced is identical to that produced by the original DNA sequence. In contrast, frameshift mutations involve the insertion or deletion of nucleotides that shift the reading frame, usually resulting in a completely different amino acid sequence downstream of the mutation. Nonsense mutations introduce a premature stop codon, leading to truncated proteins that are often nonfunctional. Missense mutations replace one amino acid with another, potentially affecting the protein's function or stability.

A silent mutation is characterized by a change in the DNA sequence that does not alter the amino acid sequence of the resulting protein. This occurs due to the redundancy in the genetic code, where multiple codons can code for the same amino acid. For instance, if a nucleotide change occurs but the new codon still codes for the same amino acid, the overall structure and function of the protein remain unchanged. Thus, the silent mutation does not have a phenotypic effect because the protein produced is identical to that produced by the original DNA sequence.

In contrast, frameshift mutations involve the insertion or deletion of nucleotides that shift the reading frame, usually resulting in a completely different amino acid sequence downstream of the mutation. Nonsense mutations introduce a premature stop codon, leading to truncated proteins that are often nonfunctional. Missense mutations replace one amino acid with another, potentially affecting the protein's function or stability.