Final answer:
Base analogs can introduce mutations by replacing normal nucleotide bases and disrupting base-pairing rules. Intercalating agents distort the DNA molecule, resulting in frameshift mutations.
Step-by-step explanation:
Base analogs are chemical mutagens that resemble normal nucleotide bases and can be incorporated into DNA during replication. They induce mutations because they often have different base-pairing rules than the bases they replace. For example, a base analog could replace cytosine with adenine, resulting in a point mutation. This change in the DNA sequence can affect how the changed strand base pairs with its complimentary strand of DNA.
Intercalating agents, another type of chemical mutagen, work by sliding between the stacked nitrogenous bases of the DNA double helix and distorting the molecule. This atypical spacing between nucleotide base pairs can lead to frameshift mutations during DNA replication. Combustion products like polycyclic aromatic hydrocarbons are particularly dangerous intercalating agents that can cause mutation-related cancers.