Which statement best describes a missense mutation's potential effect on protein function?

Which statement best describes a missense mutation's potential effect on protein function?

• A. It always inactivates the protein.
• B. It never affects function.
• C. It may alter function in various ways.
• D. It always adds a new function.

Answer: (C)

A missense mutation changes a single amino acid in a protein, and that change can have a wide range of effects on function. If the substituted amino acid is similar to the original or sits in a noncritical region, the protein may still function normally. If the change occurs near an active site, in a region important for folding, or alters charge or polarity, it can reduce activity, alter substrate specificity, or destabilize the protein. In some cases, the new amino acid creates a different interaction that changes function entirely. Because of this variability, the most accurate statement is that it may alter function in various ways. The other options are too absolute: such mutations do not always inactivate, never have an effect, or always confer a new function.

A missense mutation changes a single amino acid in a protein, and that change can have a wide range of effects on function. If the substituted amino acid is similar to the original or sits in a noncritical region, the protein may still function normally. If the change occurs near an active site, in a region important for folding, or alters charge or polarity, it can reduce activity, alter substrate specificity, or destabilize the protein. In some cases, the new amino acid creates a different interaction that changes function entirely. Because of this variability, the most accurate statement is that it may alter function in various ways. The other options are too absolute: such mutations do not always inactivate, never have an effect, or always confer a new function.