Final answer:
Glycogenolysis is phosphorylisis, not hydrolysis, due to the involvement of enzymes that transfer phosphate groups during the breakdown of glycogen.
Step-by-step explanation:
There are three reasons why glycogenolysis is phosphorylisis, not hydrolysis. First, the key enzyme involved in glycogenolysis, glycogen phosphorylase, acts on α-1→4 glycosidic linkages, which results in the release of glucose units one by one from the linear chain. This process requires the transfer of a phosphate group to the glucose molecule. Second, the remaining glucose units near the branching point are transferred to another linear chain by the enzyme glucan transferase, which involves the transfer of a phosphate group. Lastly, the glucose residue linked with α-1→6 glycosidic linkage is acted upon by the debranching enzyme, which also requires the transfer of a phosphate group.