The three general approaches used to generate mutations are radiation , chemical and transposon insertion . The first induced mutations were created by treating Drosophila with X-rays. Using this a pproach Mueller to induce lethal mutations. In addition to X-rays, other types of radiation treatments that have proven useful include gamma rays and fast neutron bombardment. Chemical mutagens work mostly by inducing point mutations .
Point mutations occur when a single base pair of a gene is changed.
These changes are classified as transitions or transversions . A transversion example is adenine being converte d to a cytosine. You can determine other examples. Two major classes of chemical mutagens are routinely used. These are alkylating agents and base analogs .