So we recycle the carbon skeleton and aspartate to fumerate and then use that to form glucose and gluconeogenesis. But the nitrogen containing group that ends up on the argininosochtenate as a result of the aspartate stays on the molecule to form arginine. Now, in the final step, step five, where we form the urea, we essentially hydrolyze the arginine by using a water molecule. We remove that urea and we also form the ornithine, the amino acid that ultimately is recycled back into the matrix of mitochondria to ultimately help this cycle continue taking place. So if we look on this molecule, the oxygen shown in blue came from the water. This carbon came from this carbon dioxide.