Which process is primarily responsible for the breakdown of glycogen?

The process primarily responsible for the breakdown of glycogen is glycogenolysis. This metabolic pathway involves the enzymatic conversion of glycogen into glucose or glucose-6-phosphate, which can be utilized for energy or released into the bloodstream to regulate blood sugar levels. Glycogenolysis occurs mainly in the liver and muscle tissues, where glycogen is stored, providing a rapid source of glucose during periods of fasting, exercise, or stress.

Glycogenesis, on the other hand, is the process of synthesizing glycogen from glucose, essentially the opposite of glycogenolysis. Gluconeogenesis refers to the creation of glucose from non-carbohydrate sources, such as amino acids or glycerol, which is a separate metabolic pathway. Glycolysis is the breakdown of glucose into pyruvate, which precedes pathways linked to energy production, but does not involve the breakdown of glycogen itself. Therefore, glycogenolysis clearly aligns with the function specified in the question regarding the breakdown of glycogen.