The electron transport chain converts food energy into an electrical gradient by shuttling electrons, reducing oxygen to water.

“and so when we eat food we're eating stored potential energy that is in a chemical form that is generally between the carbon carbon carbon hydrogen bonds as these things get reduced to simple and simpler molecules this specifically within the mitochondria takes these units and it by breaking apart the chemical bonds creates an electrical gradient by shuttling electrons outside of this membrane as they go from complex one to three and of course they each come with their own reducing agents”