What term describes a mutation that does not change the amino acid sequence?

• A. Mutation
• B. Gene expression
• C. Substitution mutation
• D. Silent mutation

Answer: (D)

A silent mutation is described here. The genetic code is degenerate, meaning multiple codons can encode the same amino acid. When a single base in a codon changes but still codes for the same amino acid, the resulting protein sequence stays unchanged. For example, GAA and GAG both code for glutamic acid; changing GAA to GAG does not alter the amino acid sequence. Because the protein remains the same, this mutation doesn’t affect the primary structure of the protein. Other terms describe broader concepts (a general mutation), processes (gene expression), or a mutation type that can affect amino acids but isn’t inherently silent, so the precise term for no change in amino acid sequence is silent mutation.