L14 – Glucose Metabolism: Glycogen and Glycolysis
Draw the structures of glucose and glycogen
Slide 3 – Structure and function of glucose and glycogen
• Osmotic pressure depends on number of glucose molecules, not size
• Glycosidic bond between carbon 1 and carbon 4 with the glucose next to it
• Bond between carbon 1 and carbon 6 = branched structure
Slide 4 – Glycogen structure
• Branched glycogen makes it easier to take glucose off because it can be taken
off at the ends of the branch
Explain the importance of liver glycogen in the maintenance of blood glucose
concentration and skeletal muscle glycogen as a metabolic fuel
Slide 5 – Role of glycogen in liver: glucose homeostasis
• Liver is sensitive to blood glucose concentration
• Acts to maintain blood glucose under the control of insulin and glucagon
- Provides glucose to cells and tissues which are dependent on glucose for metabolism
, Slide 6 – Glycogen in muscle: fuel for exercise
• Muscle is sensitive to energy needs of the tissue
• It is sensitive to adrenaline (hormonal regulation), calcium (local control), AMP, ATP
- AMP and ATP: signals whether cells need more ATP/AMP or not
Outline the enzyme reactions involved in glycogen synthesis and degradation
Slide 7 – Glycogen synthesis and breakdown
Glycogen synthesis Glycogen breakdown (glycogenolysis)
•Glycogen synthase • Glycogen phosphorylase
•Requires energy (ATP hydrolysis) • Phosphorolysis using Pi (not ATP)
- Anabolic pathway • Final product in liver: glucose
• Proceeds via an activated • Final product in muscle: glucose-6-
intermediate (UDP glucose) phosphate enters glycolysis pathway
• Synthesis and breakdown pathways are not a direct reversal of each other
- Allows independent regulation, prevents ‘futile cycle’
Slide 8 – Glycogen synthesis: ‘activation’ of glucose
• Hexokinase and glucokinase are examples of isoenzymes
• Phosphate is on carbon 6 of glucose-6-phosphate
• Phosphoglucomutase catalyses an isomerisation reaction, moving the phosphate group
• Conversion of ATP to PPi pulls the whole reaction forwards
Draw the structures of glucose and glycogen
Slide 3 – Structure and function of glucose and glycogen
• Osmotic pressure depends on number of glucose molecules, not size
• Glycosidic bond between carbon 1 and carbon 4 with the glucose next to it
• Bond between carbon 1 and carbon 6 = branched structure
Slide 4 – Glycogen structure
• Branched glycogen makes it easier to take glucose off because it can be taken
off at the ends of the branch
Explain the importance of liver glycogen in the maintenance of blood glucose
concentration and skeletal muscle glycogen as a metabolic fuel
Slide 5 – Role of glycogen in liver: glucose homeostasis
• Liver is sensitive to blood glucose concentration
• Acts to maintain blood glucose under the control of insulin and glucagon
- Provides glucose to cells and tissues which are dependent on glucose for metabolism
, Slide 6 – Glycogen in muscle: fuel for exercise
• Muscle is sensitive to energy needs of the tissue
• It is sensitive to adrenaline (hormonal regulation), calcium (local control), AMP, ATP
- AMP and ATP: signals whether cells need more ATP/AMP or not
Outline the enzyme reactions involved in glycogen synthesis and degradation
Slide 7 – Glycogen synthesis and breakdown
Glycogen synthesis Glycogen breakdown (glycogenolysis)
•Glycogen synthase • Glycogen phosphorylase
•Requires energy (ATP hydrolysis) • Phosphorolysis using Pi (not ATP)
- Anabolic pathway • Final product in liver: glucose
• Proceeds via an activated • Final product in muscle: glucose-6-
intermediate (UDP glucose) phosphate enters glycolysis pathway
• Synthesis and breakdown pathways are not a direct reversal of each other
- Allows independent regulation, prevents ‘futile cycle’
Slide 8 – Glycogen synthesis: ‘activation’ of glucose
• Hexokinase and glucokinase are examples of isoenzymes
• Phosphate is on carbon 6 of glucose-6-phosphate
• Phosphoglucomutase catalyses an isomerisation reaction, moving the phosphate group
• Conversion of ATP to PPi pulls the whole reaction forwards
