L30: The Fate of pyruvate

• What are the components used to regenerate ATP?


  ADP and Pi
• Why is NAD+ needed in cellular processes?

  NAD+ is needed for the oxidation of G-3-P.
• What happens to pyruvate under aerobic conditions?

  Pyruvate is oxidized in the citric acid cycle.
• How does the electron transport chain (ETC) function in relation to NADH?

  NADH transfers electrons to O2, forming H2O and regenerating NAD+.
• What are the fermentation products in animal muscle and some microorganisms?


  Lactate in animal muscle and ethanol in plants and yeast.
• Why is glycolysis considered central to carbohydrate breakdown?

  Glycolysis is central to carbohydrate breakdown in modern organisms, since fermentation is the primary source of energy. Most environments are temporarily anaerobic, and some are permanently anaerobic. Glycolysis can proceed in both.
• What is the overall reaction for the oxidation of glucose?

  Glucose + 6O2 → 6CO2 + 6H2O.
• Where does the citric acid cycle take place?

  The citric acid cycle takes place in the matrix of mitochondria.
• What is Acetyl Coenzyme A derived from?

  Acetyl CoA is derived from pyruvate. Coenzyme A is derived from vitamin B5.
• What is the significance of the conversion of pyruvate to acetyl CoA?

  This conversion is an irreversible reaction and is important for energy production.
• What are the advantages of multienzyme complexes?

  They minimize side reactions and coordinate regulation of reactions.
• How does the energy status of the cell affect the pyruvate dehydrogenase complex?

  Low energy status activates PDH through dephosphorylation, while high energy status inhibits it.
• What is a symptom of pyruvate dehydrogenase deficiency?

  Energy production is compromised.
• What does the sparker effect demonstrate in metabolic processes?

  Organic acids can catalytically spark the oxidation of pyruvate.
• What are the alternative names for the citric acid cycle?

  The citric acid cycle is also known as the Krebs cycle and the TCA cycle.
• What are the products of the citric acid cycle when acetyl CoA enters?

  2 CO₂, 3 NADH, FADH₂, and GTP are produced.
• What regulates the citric acid cycle?

  ATP and NADH are the principal negative regulators of the citric acid cycle.
• What are anaplerotic reactions and why are they important?

  Anaplerotic reactions replenish citric acid cycle intermediates to prevent depletion.
• What is the main source of pyruvate for the citric acid cycle?

  Pyruvate is the main source, derived from glycolysis.
• Why is pyruvate oxidised?

  Once you oxidised glucose, you get pyruvate, which still contains quite a lot of energy. Further oxidation in the citric acid cycle is needed to release that energy.