#Id: 3241
                                                        #Unit 3. Fundamental Processes
                                                        Chemical mutagens can be divided into two groups: 
those that are mutagenic to both replicating and nonreplicating DNA, such as the alkylating agents and nitrous acid; and 
those that are mutagenic only to replicating DNA, such as base analogs— purines and pyrimidines with structures similar to the normal bases in DNA.
