system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How does UV light disinfect things and what all can it disinfect?
gpt
UV radiation is ionising. That means that if it collides with certain molecules, it ionises them - puts them into a reactive state. If UV radiation ionises DNA, the DNA has a pretty high chance of changing its pattern as a result of that. Since the pattern of DNA is vital for its function, a change in the pattern can cause all sorts of problems, depending on where the change is and what the new pattern does. UV light isn't extremely penetrating, so the worst it does to humans a thick block of cells) is kill and mutate the outermost layers (the skin), but bacteria are just individual cells forming a thin sheen across a surface. Expose a bacterium to enough UV radiation and its DNA will mutate enough that the bits vital for life stop working, and the bacterium dies.