METABOLISM OF GLYCOGEN Flashcards
A branched polysaccharide of glucose units.
Glycogen
Where is glycogen stored?
Liver and muscle cells
Function of glycogen
Energy reserve and glucose buffer
What initiates glycogen synthesis
Glucose uptake and phosphorylation
Key enzyme in glycogen synthesis
Glycogen synthase
What regulates glycogen synthesis
Insulin, glucose, and ATP.
Key enzyme in glycogen breakdown?
Glycogen phosphorylase.
Initiates glycogen breakdown
Hormonal signals (e.g., glucagon, epinephrine).
What regulates glycogen breakdown
Glucagon, epinephrine, and Ca2+.
What regulates glycogen metabolism?
Hormonal regulation, allosteric control, and phosphorylation/dephosphorylation
Role of insulin in glycogen metabolism?
Stimulates glycogen synthesis
Role of glucagon in glycogen metabolism?
Stimulates glycogen breakdown
What is von Gierke’s disease?
A glycogen storage disease characterized by impaired glycogen breakdown.
How does diabetes mellitus affect glycogen metabolism?
Impairs glycogen synthesis.
Consequence of excessive glycogen breakdown
Hypoglycemia
Difference between glycogen and starch?
Glycogen is a branched polysaccharide, while starch is a linear polysaccharide.
Role of glycogenin in glycogen synthesis?
Initiates glycogen synthesis by forming a protein-glycogen complex
Effect of exercise on glycogen metabolism?
Stimulates glycogen breakdown in muscle cells.
What regulates glycogen breakdown?
a) Insulin
b) Glucagon
c) Epinephrine
d) All of the above
d) All of the above
Function of glycogen synthase?
A: Catalyzes the addition of glucose units to glycogen.
Catalyzes the addition of glucose units to glycogen.
What is the function of glycogen phosphorylase?
A: Catalyzes the breakdown of glycogen to glucose-1-phosphate.
How does insulin stimulate glycogen synthesis?
Activates glycogen synthase and inhibits glycogen phosphorylase.
hat is the role of debranching enzyme in glycogen breakdown?
Removes branches in glycogen, allowing continued breakdown.
How does glucagon stimulate glycogen breakdown?
Activates glycogen phosphorylase and inhibits glycogen synthase.
How does ATP regulate glycogen metabolism?
Inhibits glycogen breakdown and stimulates glycogen synthesis.
How does epinephrine regulate glycogen metabolism?
Stimulates glycogen breakdown and inhibits glycogen synthesis.
What is the role of Ca2+ in glycogen metabolism?
Activates glycogen phosphorylase and stimulates glycogen breakdown.
Glycogen storage disease type I, characterized by impaired glycogen breakdown.
von Gierke’s disease
Glycogen storage disease type II, characterized by impaired lysosomal glycogen breakdown
Pompe’s disease
Glycogen storage disease type III, characterized by impaired glycogen debranching.
Cori’s disease
first step in glycogen synthesis
Glucose uptake and phosphorylation.
energy source for glycogen synthesis
ATP and UTP.
What is the substrate for glycogen synthase?
UDP-glucose.
enzyme catalyzes glycogen branching?
Glycogen branching enzyme.
What enzyme catalyzes glycogen debranching?
Debranching enzyme
Group of inherited disorders characterized by deficient mobilization of glycogen or deposition of abnormal forms of glycogen
Glycogen Storage Disease
Integrates the regulation of glycogenolysis and glycogenesis by promoting simultaneous activation of phosphorylase and inhibition of glycogen synthase
Cyclic AMP
Glucagon acts on heart muscle but not on
skeletal muscle
A non-neuronal cells that stores glycogen in the brain
astrocytes
Branching involves detachment of existing?/
Glycogen chains
It synchronizes the activation of Glycogen Phosphorylase w/muscle contraction
Ca2+
Vasopressin, oxytocin and angiotensin II activates the
cAMP-independent glycogenolysis
This enzyme inactivates the glycogen phosphorylase
Protein Phosphate-1
