Glycogenolysis is the breakdown of glycogen to glucose. Which phrase correctly defines this process?

Glycogenolysis is the breakdown of glycogen to glucose. Which phrase correctly defines this process?

• A. Breakdown of glycogen to glucose
• B. Formation of glycogen from glucose
• C. Conversion of glucose to lactose
• D. Storage of glycogen

Answer: (A)

Glycogenolysis is the breakdown of glycogen into glucose. This catabolic process releases glucose units when energy is needed, especially in liver and muscle. Enzymes such as glycogen phosphorylase cleave the glycosidic bonds in glycogen, producing glucose-1-phosphate, which is then converted to glucose-6-phosphate for use in glycolysis in muscle or, in the liver, can be dephosphorylated to free glucose released into the bloodstream. That exact description—breaking glycogen down to glucose—captures what glycogenolysis does. The other phrases describe different processes: forming glycogen from glucose is glycogenesis; converting glucose to lactose isn’t a typical human metabolic step; and storing glycogen refers to glycogen storage rather than its breakdown.

Glycogenolysis is the breakdown of glycogen into glucose. This catabolic process releases glucose units when energy is needed, especially in liver and muscle. Enzymes such as glycogen phosphorylase cleave the glycosidic bonds in glycogen, producing glucose-1-phosphate, which is then converted to glucose-6-phosphate for use in glycolysis in muscle or, in the liver, can be dephosphorylated to free glucose released into the bloodstream. That exact description—breaking glycogen down to glucose—captures what glycogenolysis does. The other phrases describe different processes: forming glycogen from glucose is glycogenesis; converting glucose to lactose isn’t a typical human metabolic step; and storing glycogen refers to glycogen storage rather than its breakdown.