Overview Structure glycogen polymer of glucose login to view 2 more bullets glycogen granule core login to view 1 more bullet Function energy reserves that can provide glucose during a fast or ↑ energy demand supplies exhausted in < 24 hrs stored mainly in the liver and muscle muscle does not have glucose-6-phosphatase so it cannot release free glucose login to view 1 more bullet liver does have glucose-6-phosphatase so it can release free glucose login to view 1 more bullet Glycogenesis Glycogen synthesis Pathway glucose-6-phosphate converted to glucose-1-phosphate UDP group added to form UDP-glucose UDP-glucose added to polymer in an α-1,4 linkage catalyzed by glycogen synthase login to view 1 more bullet polymer rearranged to create α-1,6 linked branches catalyzed by branching enzyme login to view 1 more bullet Regulation glycogen synthase in liver login to view 2 more bullets in muscle login to view 2 more bullets Glycogenolysis Glycogen catabolism Pathway glucose-glucose bond broken by addition of a phosphate catalyzed by glycogen phosphorylase login to view 3 more bullets glucose-1-phosphate freed converted to glucose-6-phosphate debranching enzymes removes α-1,6 linked branches deficiency = Cori's disease (type III) liver converts glucose-6-phosphate to glucose catalyzed by glucose-6-phosphatase login to view 1 more bullet muscle puts glucose-6-phosphate into glycolysis Regulation glycogen phosphorylase in liver login to view 5 more bullets in skeletal muscle login to view 3 more bullets Glycogen Storage Diseases (Glycogenolyses) Overview all disorders have abnormal glycogen metabolism leads to an accumulation of glycogen within cells organ dysfunction remember: disorders numbered in order of pathway from end (glucose release) to beginning (breakdown of glycogen polymer) Glucose release Type I: von Gierke lacks glucose-6-phosphatase presentation login to view 8 more bullets tests login to view 2 more bullets Lysosomal pathway Type II: Pompe "trashes the Pump (heart)" lacks lysosomal α1,4-glucosidase login to view 1 more bullet presentation login to view 4 more bullets Branching/debranching Type III: Cori lacks debranching enzyme login to view 3 more bullets presentation login to view 5 more bullets Type IV: Anderson lacks branching enzyme login to view 1 more bullet presentation login to view 3 more bullets Phosphorylase Type V: McArdles lacks muscle phosphorylase login to view 3 more bullets presentation login to view 3 more bullets Type VI: Hers lacks hepatic phosphorylase login to view 1 more bullet presentation login to view 3 more bullets