What is one way that changes can occur in a dna sequence?

A change in a DNA sequence is called a mutation. Mutation occurs through a large variety of processes. The most written about in the press is of course the chemical-induced mutations. There is a large variety of chemicals that can induce mutations, most of time by binding to the DNA itself and breaking it, forcing an imperfect reparation or by blocking the replication of the DNA, which will force the replication system to duplicate it imperfectly, i really hope this helps, good luck babe!!