So we see that by attaching a carbon dioxide onto the Pyruvate, we are able to form the oxalo acetate. And that allows us to keep to maintain a specific minimal level concentration of the oxalo acetate within the citric acid cycle, which in turn allows us to maintain a specific level of the other intermediates and that allows all these important processes to continue taking place inside our cells. So for the citric acid cycle to keep up with the energy demands of the cell and the demands of producing all these different types of biological building blocks, the concentrations of the intermediate molecules within the TCA cycle must be regulated. 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.