What type of mutation involves replacing one nucleotide with another?

A substitution mutation is characterized by the replacement of one nucleotide with another in the DNA sequence. This type of mutation can lead to various outcomes, including silent mutations, missense mutations, or nonsense mutations, depending on whether the new nucleotide alters the resulting amino acid or introduces a premature stop codon.

For instance, if the original nucleotide sequence is altered by replacing one nucleotide, it could change the codon for an amino acid into a different codon. This could either have no effect on the protein (silent), change one amino acid in the protein (missense), or create a stop signal leading to a truncated protein (nonsense). This precision in altering a single nucleotide is what distinguishes substitution mutations from the other types of mutations, which involve different mechanisms of changing the genetic material.