So four CO2 molecules. Now, notice that we said that the citric acid cycle actually used to generate the high energy electrons. Notice that the cycle doesn't actually itself generate any ATP molecules. Although we do generate a total of two GTP molecules, every time two Pyruvate molecules go into the citric acid cycle, we don't actually generate any ATP molecules. So why is that? Well, because the citric acid cycle is like the gateway for forming ATP molecules.