A missense mutation typically results in

A missense mutation typically results in

• A. An amino acid change with no change in protein length
• B. A shortened protein
• C. A longer protein
• D. A complete loss of the protein

Answer: (A)

A missense mutation is a single base change that substitutes one amino acid for another in the protein sequence. Because translation still reads the same number of codons, the overall length of the polypeptide stays the same. So the typical outcome is an amino acid change with no change in protein length. The effect on function depends on how different the new amino acid is and where it occurs, as seen in examples like the sickle cell mutation, where a single amino acid swap alters protein behavior without shortening it. In contrast, shortened or longer proteins usually result from nonsense or frameshift mutations or insertions, which disrupt the reading frame or introduce premature stops, rather than a simple missense change.

A missense mutation is a single base change that substitutes one amino acid for another in the protein sequence. Because translation still reads the same number of codons, the overall length of the polypeptide stays the same. So the typical outcome is an amino acid change with no change in protein length. The effect on function depends on how different the new amino acid is and where it occurs, as seen in examples like the sickle cell mutation, where a single amino acid swap alters protein behavior without shortening it. In contrast, shortened or longer proteins usually result from nonsense or frameshift mutations or insertions, which disrupt the reading frame or introduce premature stops, rather than a simple missense change.