Texas A&M University (TAMU) BIOL 351 Fundamentals of Microbiology Exam 1 Practice

Silent mutations rely on the redundancy of the genetic code. Because most amino acids are specified by more than one codon, a nucleotide change can still code for the same amino acid. When that happens, the amino acid sequence of the protein remains unchanged, even though the DNA sequence has mutated. That’s why this statement is correct: the mutation does not alter the amino acid sequence.

Think of codons that share the same amino acid, such as GAA and GAG both coding for glutamate. A change from A to G at the third position might not affect the protein. In contrast, introducing a premature stop codon (nonsense), changing the amino acid (missense), or shifting the reading frame (frameshift) would alter the protein and aren’t silent mutations.