And so we see that stage one actually uses up two ATP molecules and no ATP molecules have been actually formed so far. Now, another important thing about this step, step three of stage one is once the step actually takes place, that commits that sugar molecule to undergoing the glycolysis process. Because before this step actually took place, that sugar molecule can be stored in the form we call glycogen. But once this step takes place, we call it the committed step because it commits that sugar to undergo that process of glycolysis. So in step three of stage one, phosphor fructokinase PFK adds a second phosphoryl group onto that sugar to make it much less stable, higher in energy and therefore much more reactive. And that will allow it to actually break down in stage two into smaller components as we'll see in the next lecture.