Editing Forward genetics (section)

=== Chemical mutagenesis ===
Chemical mutagenesis is an easy tool that is used to generate a broad spectrum of mutant alleles. Chemicals like ethyl methanesulfonate (EMS) cause random [[point mutations]] particularly in G/C to A/T transitions due to guanine alkylation.<ref name="parsch" /> These point mutations are typically loss-of-function or null alleles because they generate stop codons in the DNA sequence.<ref>{{cite journal | vauthors = Kutscher LM, Shaham S | title = Forward and reverse mutagenesis in C. elegans | journal = WormBook | pages = 1–26 | date = January 2014 | pmid = 24449699 | pmc = 4078664 | doi = 10.1895/wormbook.1.167.1 }}</ref> These types of mutagens can be useful because they are easily applied to any organism but they were traditionally very difficult to [[Gene mapping|map]], although the advent of next-generation sequencing has made this process considerably easier.

Another chemical such as ENU, also known as N-ethyl-N-nitrosourea works similarly to EMS. ENU also induces random point mutations where all codons are equally liable to change. These point mutations modify gene function by inducing different alleles, including gain or loss of function mutations in protein-coding or noncoding regions in the genome.<ref>{{Citation |last=Bucan |first=M. |title=Mouse Genetics |date=2013-01-01 |url=https://www.sciencedirect.com/science/article/pii/B9780123749840009803 |encyclopedia=Brenner's Encyclopedia of Genetics (Second Edition) |pages=486–488 |editor-last=Maloy |editor-first=Stanley |place=San Diego |publisher=Academic Press |language=en |doi=10.1016/b978-0-12-374984-0.00980-3 |isbn=978-0-08-096156-9 |access-date=2022-11-22 |editor2-last=Hughes |editor2-first=Kelly|url-access=subscription }}</ref>
[[File:Chemchemicals.png|center|thumb|487x487px|The figure shows the chemical compounds ethyl methansulfonate (shown on the left) and N-ethyl-N-nitrosourea (shown on the right).]]