A missense mutation is defined as

A missense mutation is defined as

• A. Codon changes to a different amino acid
• B. Silent mutation
• C. Frameshift mutation
• D. Codon changes to stop codon

Answer: (A)

A missense mutation happens when a single codon is changed to code for a different amino acid, altering the protein’s amino acid sequence. Because the genetic code has redundancy, not all changes alter the amino acid (those are silent mutations). If a codon becomes a stop codon, that’s a nonsense mutation, which can truncate the protein. If nucleotides are inserted or deleted and shift the reading frame, that’s a frameshift mutation, which usually alters many downstream amino acids. The impact of a missense change depends on how different the new amino acid is and where it occurs in the protein.

A missense mutation happens when a single codon is changed to code for a different amino acid, altering the protein’s amino acid sequence. Because the genetic code has redundancy, not all changes alter the amino acid (those are silent mutations). If a codon becomes a stop codon, that’s a nonsense mutation, which can truncate the protein. If nucleotides are inserted or deleted and shift the reading frame, that’s a frameshift mutation, which usually alters many downstream amino acids. The impact of a missense change depends on how different the new amino acid is and where it occurs in the protein.