The main job for the ETC (electron transport chain) is to produce ATP. Why, whats so important about ATP?
ATP has so much energy!!!!!!!!!!! As long as you got that down, you should be good. So the whole process of taking electrons and going through the electron transport chain is to make ENERGY.
Where do these electrons come from?
Free energy carriers, such as NADH and FADH, are carrying high energy electrons.
Where did these carriers get electrons? In cellular respiration, they came from Glycolysis and the Krebs cycle.
Glycolysis and the Krebs cycle donated some *electrons and hydrogen protons* to NAD+ and FAD+. By giving electrons (which have negative charges) the NAD+ reduces to NADH! FAD+ reduces to FADH