And so what UDP glucose Pyrophosphorase does is it takes this red structure here and attaches it onto this region here, and we form a urine diphosphate glucose molecule, and we also form a pyrophosphate. So this pyrophosphate is basically this section here. Now, the thing about the UDP glucose is it's a much more reactive molecule. Why? Well, because we have this additional group that contains a high negative charge. And so that makes this entire molecule, and more specifically, this Esther bond here, becomes much more reactive.