Many of the processes that take place inside our cells and generally in nature sometimes actually have negative effects. And the electron transport chain is no exception. So even though the electron transport chain is very useful to our cells because it allows us to establish a proton gradient across the inner membrane of the mitochondria which ultimately allows us to generate these high I energy ATP molecules the electron transport chain also sometimes produces these harmful byproduct molecules that can cause damage to ourselves. And because these harmful byproduct molecules are actually oxygen derivative molecules we call them reactive oxygen species. Now, before we actually talk about these molecules in slightly more detail let's remember what happens on the normal conditions in complex four of the electron transport chain. So, remember, the entire point of the electron transport chain is to actually take those high energy electrons produced by creating the NADH molecules and fadh two molecules and using those electrons to create a proton gradient.