If a mutation introduces a stop codon into a nucleotide sequence, what type of mutation is this?

A mutation that introduces a stop codon into a nucleotide sequence is classified as a nonsense mutation. This type of mutation results in the premature termination of protein synthesis. Typically, a codon is made up of three nucleotides that correspond to a specific amino acid; however, a stop codon signals the ribosome to stop translating the mRNA into a protein.

When a nonsense mutation occurs, the normal sequence is altered in such a way that it codes for a stop signal. This can lead to truncated proteins that may be nonfunctional, as the mutation prevents the full-length protein from being synthesized. Nonsense mutations can have significant effects on the phenotype of an organism, particularly if the truncated protein is essential for cellular function.

In contrast to type-specific mutations like synonymous or frameshift mutations, which affect the expression and length of the resulting protein differently, the key characteristic of a nonsense mutation is its ability to create a premature stop in translation, emphasizing its potential to disrupt normal biological processes.