Which type of mutation results in a premature stop codon?

A nonsense mutation is characterized by a change in the DNA sequence that creates a premature stop codon in the protein coding sequence. This type of mutation alters the codon that would normally code for an amino acid, resulting instead in a signal for the translation process to terminate early. The consequence of this is a truncated protein that is often nonfunctional, as the complete sequence needed for proper folding and function has not been translated.

In contrast, a missense mutation results in a change of a single amino acid in the protein, which might or might not affect the protein's function. A frameshift mutation occurs when insertions or deletions of nucleotides alter the reading frame of the genetic sequence, which can lead to significant changes in the resulting protein, including potentially creating a premature stop codon, but not necessarily. Lastly, a silent mutation changes a nucleotide but does not alter the amino acid sequence due to redundancy in the genetic code, ensuring that the full-length protein is produced without premature termination.