gluconeogenesis

• What is gluconeogenesis?

  An anabolic pathway for glucose synthesis

  
• What is glycogen metabolism?

  The process of glycogen synthesis and breakdown

  
• What is the pentose phosphate pathway?

  A metabolic pathway generating NADPH
• Why is gluconeogenesis important during exercise and starvation?

  It synthesizes glucose from non-carbohydrate sources

  
• What substrates are used in gluconeogenesis?

  Pyruvate, lactate, glycerol, amino acids

  
• Where does gluconeogenesis primarily take place?

  In the liver and kidneys
• What is the role of ATP in gluconeogenesis?

  ATP is used to drive the synthesis of glucose
• What is the first step of gluconeogenesis?

  CO2 is added to pyruvate
• What enzyme catalyzes the first step of gluconeogenesis?

  Pyruvate carboxylase
• What is the second step of gluconeogenesis?

  Conversion of oxaloacetate to phosphoenolpyruvate

  
• What enzyme is used in the second step of gluconeogenesis?

  Phosphoenolpyruvate carboxykinase
• What is the role of glycerol in gluconeogenesis?

  Glycerol enters the pathway via dihydroxyacetone phosphate

  
• What is the final step of gluconeogenesis?

  Conversion of glucose-6-phosphate to glucose
• What enzyme catalyzes the final step of gluconeogenesis?

  Glucose-6-phosphatase
• How is glycogen mobilized?

  Through phosphorolysis, debranching, and further phosphorolysis
• What is the enzyme for glycogen phosphorolysis?

  Glycogen phosphorylase
• What are glycogen storage diseases caused by?

  Defective enzymes in glycogen metabolism
• What is the role of the pentose phosphate pathway?

  Generates NADPH and synthesizes pentose sugars
• What is Type I glycogen storage disease?

  Von Gierke’s disease
• What are the stages of glycogen synthesis?

  1. Activation

  • Conversion to glucose 1-phosphate
  • Formation of UDP-glucose

  1. Polymerisation

  • Requires a primer
  • Glycogen synthase enzyme

  1. Branching

  • Branching enzyme forms branches

  
• What are the hormonal regulators of gluconeogenesis?

  • Glucagon
  • Norepinephrine and epinephrine
  • Cortisol
  • Thyroid hormone
  • Growth hormone
• What are the key steps in glycolysis?

  1. Glucose to glucose-6-phosphate (Hexokinase)
  2. Glucose-6-phosphate to fructose-6-phosphate (Phosphoglucose isomerase)
  3. Fructose-6-phosphate to fructose-1,6-bisphosphate (Phosphofructokinase)
  4. Fructose-1,6-bisphosphate to glyceraldehyde-3-phosphate and dihydroxyacetone phosphate (Aldolase)
• What are the irreversible steps in glycolysis?

  1. Hexokinase reaction
  2. Phosphofructokinase reaction
  3. Pyruvate kinase reaction
• What are the products of the pentose phosphate pathway?

  • NADPH
  • Ribulose-5-phosphate
  • Other sugars for biosynthesis
• What is the significance of NADPH in metabolism?

  • Drives biosynthesis
  • Provides reducing power for anabolic reactions
• What is the role of ATP in glycogen synthesis?

  • ATP is used to convert glucose to glucose-6-phosphate
  • ATP is also used in the formation of UDP-glucose

  
• What is the role of NADH in gluconeogenesis?

  • NADH is generated during the conversion of glyceraldehyde-3-phosphate
  • It is used in the reduction reactions of gluconeogenesis
• What is the importance of glucose-6-phosphate in metabolism?

  • It is a key intermediate in glycolysis
  • It is involved in glycogen synthesis and the pentose phosphate pathway

  
• What is the significance of the branching enzyme in glycogen synthesis?

  • It creates branches in the glycogen molecule
  • Increases the solubility and accessibility of glycogen
• What is the significance of phosphoglucose isomerase in metabolism?

  • It catalyzes the conversion of glucose-6-phosphate to fructose-6-phosphate
  • Plays a crucial role in both glycolysis and gluconeogenesis