Glycolysis

• What are the main phases of glycolysis?


  • Energy investment phase
  • Energy generation phase
• What is the total ATP yield from one mole of glucose during cellular respiration?


  32 ATP
• What are the products of glycolysis from one mole of glucose?


  2 pyruvate, 2 NADH, and 2 ATP
• What is the equation for cellular respiration?


  Glucose + 6O₂ + 32 ADP + 32 P_i → 6CO₂ + 6H₂O + 32 ATP
• What occurs during the energy investment phase of glycolysis?


  • Isomerization
  • Splitting of glucose
  • Uses 2 ATP
• What occurs during the energy generation phase of glycolysis?


  • Produces 4 ATP
  • Generates 2 NADH
• What is the role of hexokinase in glycolysis?


  Hexokinase phosphorylates glucose to trap it in the cell.
• How does phosphorylation affect glucose in glycolysis?


  It tags and traps glucose, making it more reactive.
• What is the significance of the induced fit model in hexokinase activity?


  It enhances the reaction between glucose and ATP by reducing water's interference.
• Which hexokinase isoenzyme is expressed in the liver and pancreas?


  Hexokinase IV
• How does hexokinase IV respond to hormonal signals?


  It is not inhibited by its product and responds to insulin and glucagon.
• What is the role of phospho-glucose isomerase in glycolysis?


  • Converts glucose-6-phosphate to fructose-6-phosphate
  • Utilizes acid-base catalysis
• What regulates phosphofructokinase (PFK) in glycolysis?


  ATP, ADP, pH, PEP, and citrate levels.
• Why is the phosphorylation of fructose-6-phosphate significant in glycolysis?


  It prevents the reformation of glucose-6-phosphate, ensuring unidirectional flow.
• What are the fates of pyruvate after glycolysis?


  • Converted to acetyl-CoA for the Krebs cycle
  • Converted to lactate in anaerobic conditions
  • Used in gluconeogenesis
• What is the role of pyruvate dehydrogenase in cellular respiration?


  It converts pyruvate into acetyl-CoA.
• What vitamins are required as co-factors for the pyruvate dehydrogenase complex?


  Thiamine (B1), niacin (B3), riboflavin (B2), and pantothenic acid (B5).
• What are the consequences of pyruvate dehydrogenase deficiency?


  • Insufficient acetyl-CoA production
  • Neurological and muscle degeneration
  • Lactic acidosis
• What is the main product of the link reaction?


  Acetyl-CoA
• What is the role of pyruvate carboxylase?


  It catalyzes anaplerotic reactions to replenish Krebs cycle intermediates.
• What are the two main phases of glycolysis?


  • Phase 1: Energy investment
  • Phase 2: Energy generation
• How does glycolysis contribute to cellular respiration?


  It provides ATP and pyruvate for further metabolic processes.
• What is anaplerosis and cataplerosis?

  • Anaplerosis: Reactions that feed the Krebs cycle
  • Cataplerosis: Reactions that deplete the Krebs cycle
• What is the final product of glycolysis?


  Pyruvate
• What happens to lactate in the liver?

  Lactate is reoxidized to pyruvate to produce glucose.
• What is the significance of glycolysis in muscle cells?


  • Provides ATP under anaerobic conditions
  • Supports energy needs during intense exercise
• What are the regulatory nodes in glycolysis?


  • Hexokinase
  • Phosphofructokinase
  • Pyruvate kinase
• What is the role of G3P dehydrogenase in glycolysis?


  It catalyzes the conversion of G3P to 1,3-bisphosphoglycerate.
• What is the significance of substrate-level phosphorylation in glycolysis?


  It directly generates ATP from ADP during glycolysis.
• How does the energy yield of glycolysis compare to oxidative phosphorylation?


  Glycolysis yields less ATP than oxidative phosphorylation.
• What are the key enzymes involved in glycolysis?

  • Hexokinase
  • Phosphofructokinase
  • Aldolase
  • G3P dehydrogenase
  • Pyruvate kinase
• What is the role of phosphoglycerate kinase in glycolysis?


  It catalyzes the conversion of 1,3-bisphosphoglycerate to 3-phosphoglycerate.
• What is the function of triose phosphate isomerase?


  It interconverts dihydroxyacetone phosphate and glyceraldehyde-3-phosphate.
• How does the deficiency of triose phosphate isomerase affect the body?


  It leads to severe hemolytic anemia and neurodegeneration.
• What are the consequences of deficiencies in glycolytic enzymes?


  • Hemolytic anemia
  • Myopathy
  • Central nervous system disorders
  • Growth retardation
• What is the role of pyruvate kinase in glycolysis?


  It catalyzes the conversion of phosphoenolpyruvate to pyruvate.
• How does hormonal regulation affect pyruvate kinase activity?


  It is regulated by ATP/ADP levels and hormonal signals.
• What are the metabolic pathways that respond to different conditions?


  • Phosphagen system: anaerobic and fast ATP replenishment
  • Glycolysis: anaerobic pathway for ATP needs
  • Oxidative phosphorylation: aerobic and efficient ATP yield
• What is the primary function of glycolysis?


  To produce ATP and pyruvate from glucose.
• What is the relationship between glycolysis and the Krebs cycle?


  Pyruvate from glycolysis enters the Krebs cycle for complete oxidation.