So we must maintain a minimal level of those intermediates. So when our cells, for instance, deplete the concentration of oxalo acetate by, for instance, producing all these different types of building blocks, we essentially want to replenish the concentration via specific type of reaction that is catalyzed by Pyruvate carboxylate. So in this step, we attach a CO2 molecule onto Pyruvate to form the four carbon molecule known as oxalo acetate. In the process, we hydrolyze an ATP by using water to basically drive the synthesis of this molecule in this general direction. So when we have plenty of ATP molecules inside our body, because if our energy value is low we have a relatively high concentration of ATP, under these conditions the oxyloacetate will be transformed into a variety of products. Why?