Well, glycogen, glycogen breakdown, also known as glycogen degradation, is the process by which we carry out three different steps to basically release the glucose molecule from glycogen. And this process actually involves four different enzymes, as we'll see in just a moment. So let's discuss the first step of glycogen breakdown. Now, the first step is known as phosphoralysis, and this process is catalyzed by an enzyme known as glycogen phosphorylase. Now, glycogen phosphorylase uses an orthophosphate molecule to actually cleave to break an alpha one four glycosytic bond between a terminal glucose molecule that contains a free hydroxyl group on the fourth carbon and the JSON glucose molecule. And this can be seen in the following picture.