And on top of that, we can also use oxalo acetate to form other amino acids and purity nitrogenous bases as well as pyrimidine nitrogenous bases. So the point is, this is the center of metabolism. All the fuel molecules that we use to break down into ATP, this is where the fuel molecules end up. On top of that, we can use these intermediates of the citric acid cycle to basically produce many different types of amino acids and bases and glucose molecules as well as other important groups used by the enzymes and proteins of Arabani. Now, what I'd like to focus on in this lecture briefly is the following idea. Because the citric acid cycle is so important, we have to make sure that the concentrations, the levels of these intermediate molecules is actually kept in check.