Final answer:
Chemical mutagens can induce different types of gene mutations by acting as base analogs or modifying existing nucleotide bases. Base analogs can be incorporated into DNA during replication and result in mutations due to their different base-pairing rules. Chemicals that modify nucleotide bases can cause changes in base-pairing rules, leading to mutations.
Step-by-step explanation:
Chemical mutagens can induce different types of gene mutations. One type of mutation is caused by base analogs, which are chemicals that are similar in structure to normal nucleotide bases and can be incorporated into DNA during replication. These base analogs can result in mutations because they have different base-pairing rules than the bases they replace.
Another type of mutation is caused by chemicals that modify existing nucleotide bases. For example, nitrous acid can deaminate cytosine, converting it to uracil, which then pairs with adenine instead of guanine during replication, leading to a mutation.