Glycogen phosphorylase reaction

The glycogen phosphorylase reaction.

The branched polysaccharide glycogen represents the main storage form of glucose in the body. Glycogen granules are especially prominent in the cells of muscle and liver tissue. The processes of glycogen synthesis and glycogen degradation are important topics in MCAT preparation for several reasons. Firstly, the enzymatic processes are illustrative of several important general principles in biochemical mechanisms. Additionally, glycogen metabolism is mediated by hormonal control. It plays an important part in blood glucose regulation. This makes glycogen metabolism a favorite topic for the discussion of physiological and metabolic integration as well as signal transduction mechanisms.

WikiPremed Resources

Learning Goals

Proficiency 

Understand which types of glycosidic linkages are present in glycogen and be prepared to describe the structure of glycogen granules.

Be able to describe the mechanism of glycogen phosphorylase.

Comprehend why glycogen debranching enzyme is required for the breakdown of glycogen in addition to glycogen phosphorylase.

Know the steps of the glycogen synthetase mechanism including the role of UDP-glucose pyrophosphorylase in setting the stage.

Understand the intracellular signaling and regulatory mechanisms by which glycogen sythetase is nearly inactive when glycogen phosphorylase is active. Be prepared to relate these mechanisms hormonal control by insulin, glucagon, and epinephrine.

Suggested Assignments

The question server contains a general section covering basic concepts from gluconeogenesis, the pentose phosphate pathway, glyocogen metabolism, fatty acid metabolism, the urea cycle, and metabolic integration. After review complete the crossword puzzle for energy metabolism. Here is the solution to the puzzle.

Review the web resources for glycogen metabolism.

Conceptual Vocabulary for Glycogen Metabolism