This cycle runs once per pyruvate, thus twice per glucose.
Per glucose, the Krebs Cycle produces 6 CO2 (discarded as waste in animal cells, recaptured for photosynthesis in plant cells).
Electron Transport System (oxidative phosphoryllation) (occurs in the membranes of the cristae of the mitochondria)
The hydrogens on the reduced NAD’s and FAD’s are split into one H+ and one e- each.
The electrons are used to perform a series of reduction/oxidation chemical reactions which produce a lot of energy, which is used to make 34 ATP’s (probably via chemiosmotic coupling) and quite a bit of heat.
Electron pairs from NAD red result in the production of 3 ATP’s each; those from FADred produce only two.
At the end, the electrons are reunited with their H+ and joined to ½ O2 (from the air) to produce H2O.
38 ATP’s are produced from the oxidation of one glucose: 4 are produced by glycolysis, but two must be used up to gain these four; 2 are produced by the two rounds of the Krebs Cycle; and 34 are produced by the electron transport system.