Microbiology
They competitively inhibit bacterial DNA polymerase by mimicking deoxynucleotide triphosphates and are therefore strictly bacteriostatic.
They methylate bacterial DNA, preventing DNA polymerase binding and halting replication without causing breaks.
They bind bacterial topoisomerase/gyrase and block religation of cut DNA, producing lethal double-strand breaks.
They incorporate into DNA as false nucleotides causing chain termination during replication in both bacteria and human cells.