A base-pair substitution that results in a codon that codes for a different amino acid is best described as a

A base-pair substitution that results in a codon that codes for a different amino acid is best described as a

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

Answer: (A)

A base-pair substitution that changes a codon to code for a different amino acid is a missense mutation. This is a non-synonymous change, meaning the protein sequence is altered at that position, which can affect the protein’s properties or function depending on the new amino acid and its role in the protein. For example, a codon change that swaps Glu for Lys introduces a different type of side chain, potentially altering charge and interactions at that site. In contrast, a nonsense mutation creates a stop codon and truncates the protein; a silent mutation changes the DNA but still encodes the same amino acid due to codon redundancy; and a frameshift mutation results from insertions or deletions that shift the reading frame, usually altering many downstream amino acids.

A base-pair substitution that changes a codon to code for a different amino acid is a missense mutation. This is a non-synonymous change, meaning the protein sequence is altered at that position, which can affect the protein’s properties or function depending on the new amino acid and its role in the protein. For example, a codon change that swaps Glu for Lys introduces a different type of side chain, potentially altering charge and interactions at that site.

In contrast, a nonsense mutation creates a stop codon and truncates the protein; a silent mutation changes the DNA but still encodes the same amino acid due to codon redundancy; and a frameshift mutation results from insertions or deletions that shift the reading frame, usually altering many downstream amino acids.