Metabolism, Glycolysis, Regulation

• What is metabolism?

  The set of all chemical reactions in organisms
• What are the two main components of metabolism?

  Catabolism and anabolism
• What is catabolism and its function?

  • Breakdown of complex molecules
  • Releases energy
  • Provides energy for cellular functions
• What is anabolism and its function?

  • Synthesis of complex molecules
  • Uses energy
  • Builds cell components
• What are carbohydrates composed of?

  Carbon, hydrogen, and oxygen
• What is the primary function of carbohydrates?

  To serve as the primary energy source
• What are the three main types of carbohydrates?

  1. Monosaccharides
  2. Disaccharides
  3. Polysaccharides
• What are the functions of carbohydrates?

  • Provide energy for immediate use
  • Store energy for future use
  • Contribute to structural components in cells
• What is glycolysis?

  A metabolic pathway that breaks down glucose
• What are the end products of glycolysis?

  ATP and NADH
• How many reactions occur in glycolysis?

  10 sequential reactions
• What is the net gain of ATP from glycolysis?

  2 ATP
• How much ATP is required to start glycolysis?

  2 ATP
• What is produced alongside ATP during glycolysis?

  2 NADH
• What is pyruvate?

  The end product of glycolysis
• What are the key features of glycolysis?

  1. Energy Investment Phase: Requires 2 ATP
  2. Energy Generation Phase: Produces 4 ATP and 2 NADH
• What are the regulation points in glycolysis?

  • Hexokinase (HK)
  • Phosphofructokinase (PFK)
  • Pyruvate Kinase (PK)
• What does hexokinase do in glycolysis?

  Phosphorylates glucose to glucose-6-phosphate
• What inhibits hexokinase?

  High levels of glucose-6-phosphate
• What activates phosphofructokinase (PFK)?

  AMP, ADP, and F2,6BP
• What inhibits phosphofructokinase (PFK)?

  ATP and citrate
• What activates pyruvate kinase (PK)?

  FBP
• What inhibits pyruvate kinase (PK)?

  ATP and acetyl CoA
• What are the key steps in the glycolytic pathway?

  1. Glucose → Glucose-6-phosphate (HK)
  2. G6P → Fructose-6-phosphate (PGI)
  3. F6P → Fructose-1,6-bisphosphate (PFK)
  4. FBP → G3P and DHAP (Aldolase)
  5. DHAP → G3P (TPI)
  6. G3P → 1,3-Bisphosphoglycerate (G3PDH)
  7. 1,3-BPG → 3-Phosphoglycerate (PGK)
  8. 3PG → 2-Phosphoglycerate (PGM)
  9. 2PG → Phosphoenolpyruvate (Enolase)
  10. PEP → Pyruvate (PK)
• What are the regulation mechanisms in glycolysis?

  • Allosteric Control
  • Covalent Modification
• What is the difference between aerobic and anaerobic glycolysis?

  • Aerobic: Requires oxygen, produces more ATP
  • Anaerobic: No oxygen, produces less ATP
• What is the citric acid cycle also known as?

  Krebs cycle
• What is the role of the citric acid cycle?

  Completes the oxidation of glucose
• What are the key outputs of the citric acid cycle?

  • 3 NADH
  • 1 FADH2
  • 1 GTP (equivalent to ATP)
  • 2 CO2
• What is the significance of the citric acid cycle?

  • Produces high-energy electron carriers
  • Powers ATP production through oxidative phosphorylation
• What are the key enzymes in the citric acid cycle?

  1. Citrate Synthase
  2. Aconitase
  3. Isocitrate Dehydrogenase
  4. α-Ketoglutarate Dehydrogenase
  5. Succinyl CoA Synthetase
  6. Succinate Dehydrogenase
  7. Fumarase
  8. Malate Dehydrogenase
• What are the intermediates in the citric acid cycle?

  • Citrate
  • Isocitrate
  • α-Ketoglutarate
  • Succinyl CoA
  • Succinate
  • Fumarate
  • Malate
  • Oxaloacetate
• What transformations occur in the citric acid cycle?

  • Acetyl CoA + Oxaloacetate → Citrate
  • Citrate → Isocitrate
  • Isocitrate → α-Ketoglutarate
  • α-Ketoglutarate → Succinyl CoA
  • Succinyl CoA → Succinate
  • Succinate → Fumarate
  • Fumarate → Malate
  • Malate → Oxaloacetate
• What is the regulation of the citric acid cycle?

  • Regulated by substrate availability
  • Feedback inhibition by NADH and ATP
• What is the role of NADH in energy production?

  It acts as an electron carrier
• What is the role of FADH2 in energy production?

  It acts as an electron carrier
• What is GTP equivalent to?

  ATP
• What is the significance of the citric acid cycle in metabolism?

  It generates energy carriers for ATP production
• What are the key differences between aerobic and anaerobic glycolysis?

  • Aerobic: Produces 36-38 ATP, converts pyruvate to acetyl CoA
  • Anaerobic: Produces 2 ATP, converts pyruvate to lactate or ethanol
• What is the overall importance of glycolysis and the citric acid cycle?

  • Provides energy for cellular functions
  • Supplies intermediates for biosynthetic pathways