Well if we don't have many ATP molecules then the glycosis process will continue and will form many ATP molecules and also Pyruvate molecules. And because where under aerobic conditions the peruvate will essentially enter the mitochondria and carry out the citric acid cycle. Now one of the initial intermediates of the citric acid cycle is a molecule known as citrate and citrate is ultimately formed from the pyruvate molecule that enters that mitochondria. Now, eventually, after we form many ATP molecules and the concentration of ATP rises and the energy charge of the cell increases, we will not want to form any more ATP molecules. Because what that will mean is not only will we have enough ATP molecules to go around, we'll also have enough citrate molecules to actually create ATP molecules. And so in this particular case if we have plenty of ATP molecules that means we'll have plenty of Pyruvate molecules and plenty of citrate molecules circling in that crept cycle.