any agent capable of altering the genetic constitution of a cell by changing the structure of the hereditary material, deoxyribonucleic acid (DNA). Many forms of electromagnetic radiation (e.g., cosmic rays, X rays, ultraviolet light) are mutagenic, as are a variety of chemical compounds. The effects of some mutagens are potentiated (increased) or suppressed in some organisms by the presence of certain other, nonmutagenic substances; oxygen, for example, makes cells more sensitive to the mutagenic effects of X rays.
We welcome your comments. Any revisions or updates suggested for this article will be reviewed by our editorial staff. Contact us here.
Regular users of Britannica may notice that this comments feature is less robust than in the past. This is only temporary, while we make the transition to a dramatically new and richer site. The functionality of the system will be restored soon.