system
Given the following post, respond as if you're commenting on Reddit:
human
How does antibacterial soap kill bacteria?

I understand mechanical agitation and good ol’ water can wash away bacteria, but what exactly does antibacterial soap do. Answers that involve organic chemistry are welcome!
gpt
Most antibacterial soaps contain triclosan, which inhibits one of the chemical reactions required for the production of fatty acids that are used to make cell membranes. In high doses, through this and other mechanisms, this causes bacteria to die. In low doses it causes bacteria to stop growing. Humans also make fatty acids and cell membranes, but our chemical pathway for it is different enough that it is unaffected by triclosan (we do have other molecules in our body that are affected by triclosan, but only at much higher doses than you get from washing your hands with it).

As a side note, antibacterial soaps have proven totally unnecessary for ordinary daily activities. The point of washing is to get the bacteria off your hands - it doesn't matter if you kill them on their way down the drain. The only time you should want to aggressively kill all the bacteria on your skin is when you're going into surgery (either as a patient or a doctor), or have just been exposed to something particularly dangerous.

This is all (both the mechanism and the lack of necessity) totally different from hand sanitizer, as in the stuff you rub on your hands that quickly dries by itself. Better to just wash your hands, but it has a convenience factor over soap. Most hand sanitizers are just good ol' fashioned alcohol, mixed with some gelling agent.