Explain the process of the electron transport chain. where do the molecules used in the process come from? what powers the process?

Process of Electron Transport Chain (ETC), is a series of transferring from electron donors to their acceptors.  It basically means a transfer from high energy molecule to a low-energy molecule.  This process of extracting energy by transfer is classified as a chemical reaction and we see it is the path taken of cellular respiration (NADH) and FADH2) and in photosynthesis, NADPH.  It starts with an electron, NADH and FADH2, when the electron donors release a proton gradient and it creates an imbalance.  Think of it as a see-saw with one heavy person on one end and a lighter one on the other end.  The protons actually attempt to defuse back across this see-saw of a membrane and it releases energy during the cross over which we call Chemiosmosis.