Final answer:
A nonsense mutation results in a premature termination of translation, leading to a truncated and often non-functional protein product.
Step-by-step explanation:
A nonsense mutation is a specific type of genetic mutation where a codon is changed into a stop codon, leading to the premature termination of translation. This results in a protein that is often truncated and non-functional due to the abrupt halt in protein synthesis. The earlier in the gene the mutation occurs, the more impactful it can be, as it can cause the resulting protein to be significantly shorter and likely dysfunctional. This is different from a missense mutation, which replaces one amino acid with another, potentially having less severe effects if the new amino acid has similar properties to the original one.