CK-12 Foundation
Ck 12: Causes of Mutation
[Free Registration/Login may be required to access all resource tools.] Learning activity defines mutagen, covers the causes of mutation, and gives examples of spontaneous mutations.
City University of New York
Bio Lab Module: Breaking the Genetic Code
Try this interactive module from the Brooklyn College to help understand the genetic code and how changes in the code effect the final protein product.
Other
The Msds Hyper Glossary: Mutagen
Definition of Mutagen, plus information on related terms such as Carcinogen and Teratogen.
CK-12 Foundation
Ck 12: Biology: Mutation Causes
[Free Registration/Login may be required to access all resource tools.] Covers the causes of mutation.