The key enzyme that is needed for glycogenesis the building of glycogen molecules is glycogen synthase. So this is the enzyme that basically catalyzed the formation of alpha one four glycosytic bonds. It basically connects the glucose molecules within the glycogen. So it extends and elongates the glycogen polymer chain. Now this enzyme enzyme is not only actually used to build up the glycogen chain it is also actually used to control the rate at which glycogen synthesis actually takes place. So we can actually turn off the glycogen synthase enzyme and that in turn turns off the process of glycogenesis.