Question

A mutation that involves a single nucleotide is called.

Answer 1

Point mutations are a broad category of mutations that describe a change in a single nucleotide of DNA, such as a substitution for another nucleotide, deletion of a nucleotide, or insertion of a single nucleotide into the DNA, resulting in DNA that differs from the normal or wild type gene...

or you can say:

Point mutations are a large category of mutations that describe a change in single nucleotide of DNA, such that that nucleotide is switched for another nucleotide, or that nucleotide is deleted, or a single nucleotide is inserted into the DNA that causes that DNA to be different from the normal or wild type gene ...