If a mutation changes a codon but still codes for the same amino acid, what is the effect on the resulting polypeptide?

If a mutation changes a codon but still codes for the same amino acid, what is the effect on the resulting polypeptide?

• A. Change in amino acid sequence
• B. Introduction of a premature stop codon
• C. No change in amino acid sequence
• D. Frameshift mutation

Answer: (C)

When a codon changes but still encodes the same amino acid, the amino acid sequence of the protein remains unchanged. This is because multiple codons can specify the same amino acid due to the degeneracy of the genetic code. Such a mutation is called a silent (synonymous) mutation, and the primary structure of the polypeptide is the same, so the protein’s overall properties are usually preserved. In rare cases, there might be subtle effects on translation efficiency or folding due to codon usage, but the actual amino acid sequence doesn't differ. If a different amino acid were incorporated, the protein’s sequence would change. If a premature stop codon appeared, the polypeptide would be truncated. If nucleotides were inserted or deleted not in multiples of three, the reading frame would shift, altering downstream amino acids (a frameshift).

When a codon changes but still encodes the same amino acid, the amino acid sequence of the protein remains unchanged. This is because multiple codons can specify the same amino acid due to the degeneracy of the genetic code. Such a mutation is called a silent (synonymous) mutation, and the primary structure of the polypeptide is the same, so the protein’s overall properties are usually preserved. In rare cases, there might be subtle effects on translation efficiency or folding due to codon usage, but the actual amino acid sequence doesn't differ.

If a different amino acid were incorporated, the protein’s sequence would change. If a premature stop codon appeared, the polypeptide would be truncated. If nucleotides were inserted or deleted not in multiples of three, the reading frame would shift, altering downstream amino acids (a frameshift).