Electron Transport Chain: happens in the mitochondria of a cell. This is a process in which electrons are passed between different molecules, oxygen and hydrogen, to yield water and 3 energy molecules. The energy is in the form of ATP, adenosine triphosphate.

Cited: "DNA and Proteins are Key molecules of the cell Nucleus." DNA from the Beginning. DNAFTB.org. Updated 2006. Accessed 3 Dec 2006. http://www.dnaftb.org/dnaftb/15/concept/index.html