What is a point mutation?

Point mutation is a type of mutation in which one or few nucleotide sequences in DNA undergo changes, which alters the structure of the chromosome. There are three main types of changes that a nucleotide may undergo – insertion, substitution, and deletion. In an insertion mutation, an extra nucleotide is inserted into the sequence. In a substitution mutation, one nucleotide is replaced by another nucleotide. In a deletion mutation, a nucleotide is deleted from the sequence.