Metabolic pathways Glycogen Flashcards
What is glycogen?
Main storage form of glucose in liver and muscle
What are the differences in storage of liver and muscle glycogen?
Liver- Glucose broken down is released to the red blood cells, Brain etc
Muscle- Glucose broken down can only supply that muscle
What is Glycogenesis?
Synthesis of glycogen from glucose
What is Glycogenolysis?
Glycogen breakdown releasing glucose
Glycogenolysis peaks during non meal times. T/F?
True
How is glucose derived overnight during sleep?
By gluconeogeneis- glucose produced by breaking down non carbohydrates
Glycogen is a polymer made from glucose monomers joined by what type of bonds?
a-1,4 glycosidic
Branches- a1,6 glycosidic bonds
Why is glycogenin important?
Glycogenin- attaches 4 glucose molecules together
Provides a primer which can be used to add/ remove glucose molecules to form or breakdown glycogen
Glucose is directly converted to glycogen. T/F?
False.
What are the steps of glucose conversion to glycogen? (4)
- Glucose–> glucose-6-phosphate
- Glucose-6-phosphate–>Glucose-1-phosphate
- Glucose 1 phosphate–> UDP glucose
- UDP glucose + (glucose)n+1 –> Glycogen
What important enzyme controls the process of adding glucose to UDP glucose to form glycogen?
Glycogen synthase (rate limiting enzyme)
Whys is UDP glucose important?
Activated form of glucose, allows glucose to be added to glycogen at the end of its chain
What enzyme introduces the branches of glycogen formed by a1,6 glycosidic bonds?
Transglycosylase
Which enzyme catalyses glycogenolysis?
Glycogen phosphorylase (rate limting enzyme)
Action of glycogen phosphorylase?
Adds phosphate to glycogen
Produces glycogen-1-phosphate
What enzyme converts glucose-1-phosphate to glucose-6-phosphate?
Phosphoglucomutase
What happens to glucose-6-phosphate in the liver and muscle?
- Liver- dephosphorylated and glucose produced is used
2. Muscle - Cant be dephosphorylated so enters glycolysis and TCA cycle
What happens in glycogen storage disease?
Defect in various of the above enzymes causes excessive glycogen storage in liver, muscle or both
