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Questions and Answers
What is the structure of glycogen?
What is the structure of glycogen?
A branched polymer of α-d-glucose.
Where does glycogen mainly occur in the body?
Where does glycogen mainly occur in the body?
Liver and muscle.
What is the main function of liver glycogen?
What is the main function of liver glycogen?
To maintain blood glucose concentration in the fasting state.
What is the process of glycogen synthesis called?
What is the process of glycogen synthesis called?
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Muscle glycogen directly yields free glucose.
Muscle glycogen directly yields free glucose.
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Glycogen storage diseases are characterized by deficient mobilization of glycogen or deposition of _____ forms of glycogen.
Glycogen storage diseases are characterized by deficient mobilization of glycogen or deposition of _____ forms of glycogen.
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What is the role of UDP-glucose in glycogen biosynthesis?
What is the role of UDP-glucose in glycogen biosynthesis?
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Which process occurs mainly in muscle and liver for glycogen synthesis?
Which process occurs mainly in muscle and liver for glycogen synthesis?
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Study Notes
Glycogen Structure and importance
- Glycogen is the major carbohydrate storage in animals
- It's a branched polymer of α-d-glucose
- Found mainly in the liver and muscle, with smaller amounts in the brain
- Liver glycogen is used to maintain blood glucose concentration
- Muscle glycogen, stored in larger amounts than liver, acts as a readily available source of glucose-1-phosphate for glycolysis
- Liver glycogen depletes quickly after fasting, while muscle glycogen does not directly yield free glucose
Glycogen Synthesis - Glycogenesis
- Glycogen biosynthesis involves UDP-glucose
- Glucose is phosphorylated by hexokinase (muscle) or glucokinase (liver) to glucose-6-phosphate
- Glucose-6-phosphate is isomerized to glucose-1-phosphate by phosphoglucomutase
- Glucose-1-phosphate then reacts with UTP to form UDPGlc
- This reaction is catalyzed by UDPGlc pyrophosphorylase, which is not a regulatory step
- UDPGlc is the active nucleotide that allows for glycogen synthesis
Branching in Glycogen
- The formation of branch points is slower than the addition of glucose units to a linear chain
- This is why some endurance athletes practice carbohydrate loading
- This leads to rapid glycogen synthesis with fewer branch points than normal
- This is done by exhausting the muscle glycogen, then consuming a high-carbohydrate meal
Glycogen Storage Diseases
- These are inherited disorders where deficient mobilization of glycogen or deposition of abnormal glycogen occurs
- This leads to liver damage and muscle weakness
- Some are fatal
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Description
Explore the vital role of glycogen in animal carbohydrate storage and its synthesis process known as glycogenesis. This quiz delves into its structure, significance in liver and muscle, and the biochemical pathways involved in glycogen formation.
