The stages are: Glycolysis, Krebs Cycle, Electron Chain Transport
the first stage is Glycolysis, which is the breaking up of glucose a 6 carbon sugar into two 3 carbon molecules called Pyruvate. The three carbon sugar, or Pyruvate, is then broken up into a two carbon molecule called Acetyl CoA, this molecule enters the Krebs Cycle where carbons are added and taken off to create energy(known as ATP), and last is the electron chain transport.