Glycogen Metabolism
Start with the big picture
Glycogen is a branched glucose reserve stored as hydrated granules in the cytosol. Liver glycogen helps maintain blood glucose, while muscle glycogen supplies local energy for contraction. Synthesis uses UDP-glucose and involves glycogenin, glycogen synthase, and a branching enzyme; breakdown relies on glycogen phosphorylase and a debranching enzyme. Hormonal signals, phosphorylation, and allosteric effectors coordinate these opposing pathways. A key distinction is that the liver can convert glucose-6-phosphate to glucose for export, whereas muscle lacks this capacity. The lesson also outlines glycogen storage diseases, including the features of Type I disease described in the source.
What you'll learn
- Describe glycogen’s structure and contrasting roles in liver and muscle.
- Outline glycogen synthesis, including initiation, elongation, branching, and UDP-glucose formation.
- Explain glycogen breakdown and the conversion of glucose-1-phosphate to glucose-6-phosphate.
- Compare hormonal, covalent, and allosteric regulation of glycogen metabolism.
- Relate glycogen pathway defects to the glycogen storage diseases introduced in the lesson.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
