Cytotoxins operate by targeting various cellular components such as cell membranes, proteins, and DNA. They may cause disruption of the cell membrane integrity, inhibit protein synthesis, or induce DNA damage. The mechanism of action depends on the type of cytotoxin. For instance, some cytotoxins, like ricin, inactivate ribosomes, while others, such as diphtheria toxin, inhibit protein synthesis by modifying elongation factors.