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Reactive Oxygen Species (ROS)

Reactive oxygen species are

  • molecules like hydrogen peroxide (#5)
  • ions like the hypochlorite ion (#6)
  • radicals like the hydroxyl radical (#3). It is the most reactive of them all; note how it differs from the hydroxyl ion (#4).
  • the superoxide anion (#2) which is both ion and radical.

A radical


Bioluminescence is the ability of living things to emit light. It is found in

  • many marine animals, both invertebrate (e.g., some cnidarians, crustaceans, squid) and vertebrate (some fishes);
  • some terrestrial animals (e.g., fireflies, some centipedes);
  • some fungi and bacteria (photo at right)

The molecular details vary from organism to organism, but each involves

  • a luciferin, a light-emitting substrate
  • a luciferase, an enzyme that catalyzes the reaction
  • ATP, the