The strategy of glycolysis and the citric acid cycle as energy converters is easier to understand with the help of the summary flow chart opposite, and the free energy diagram on the next page, which is a more complete version of the one introduced earlier.

Each intermediate in glycolysis and the citric acid cycle now is shown at its proper energy level below glucose. The pump-priming nature of the steps from glucose to G3P now is apparent, as are the large free energy drop where NADH is made and the two smaller drops where energy is stored as ATP during glycolysis. Since one molecule of glucose yields two molecules of pyruvate, everything to the right of FDP is drawn in terms of two molecules at a time. The 140 kcal drop in free energy from glucose (Glu) to pyruvate (Pyr) during glycolysis is relatively small compared with the much larger drop to acetyl CoA and eventually to oxaloacetate. The numbers on the individual stairsteps represent the free energies of those molecules relative to glucose as the starting point.