Cell Biology/Energy supply/Electron transport
This stage involves using the NADH molecules produced previously, along with electrons from reduced electron carriers, to from molecules of ATP. In eukaryotes this process takes place in the mitochondria, while in oxygen tolerant prokaryotes it takes place in the cell membrane. Some eukaryotic cells, such as red blood cells, do not have mitochondria and therefore cannot use the electron transport chain to produce energy.
In plant cells, energy is used from the sun to start chemical reactions which create ATP.