Biochemistry · MU Pleven

16. Aerobic Glycolysis. Connection with Citric Acid Cycle and Electron Transfer Chain. Glycerophosphate Shuttle and Malate Shuttle to Transport Reducing Equivalents to Mitochondria. Energetic balance.

Covers aerobic glycolysis as the breakdown of glucose to pyruvate in the presence of oxygen, then walks through its three stages: the energy investment phase, the splitting phase and the energy yield phase. It goes on to link pyruvate, the citric acid cycle and the electron transport chain, and compares the glycerophosphate and malate shuttles for moving cytosolic NADH into mitochondria. A table and an overall equation summarise the net ATP yield, which the note gives as 5 to 7 ATP per glucose.

Inside: 13 sections · 5 labelled pictures · 1 table · 1 formula · 30 flashcards · 4 min

Topic 16 of 76 in the MU Pleven syllabus for Biochemistry (Medicine, Year 2). The free AceMed note covers it in 13 sections, about 444 words (4 min of reading), with 30 flashcards.

In this note

  1. Aerobic Glycolysis.
  2. Aerobic Glycolysis
  3. Definition
  4. Overview of the Process
  5. Major Stages of Aerobic Glycolysis
  6. Fate of Pyruvate in Aerobic Conditions
  7. Connection Between Glycolysis, Citric Acid Cycle, and ETC
  8. Transport of NADH from Cytosol to Mitochondria
  9. Glycerophosphate Shuttle
  10. Malate-Aspartate Shuttle
  11. Energetic Balance of Aerobic Glycolysis
  12. Overall Equation of Aerobic Glycolysis
  13. Biological Importance

Definition

  • Aerobic glycolysis is the process of glucose breakdown to pyruvate in the presence of oxygen.
  • It occurs in the cytoplasm of all cells.
  • Unlike anaerobic glycolysis, pyruvate formed here is oxidatively decarboxylated to acetyl-CoA, which then enters the Krebs cycle.
  • It provides ATP and reducing equivalents (NADH + H⁺) for oxidative phosphorylation.

Overview of the Process

  • Starting molecule: Glucose
  • End product: Pyruvate (which is further converted to acetyl-CoA in the mitochondria)
  • Net result: Energy production (ATP) and reducing power (NADH)

Major Stages of Aerobic Glycolysis

Stage I – Energy Investment Phase (Preparatory Phase)

  • Glucose is phosphorylated and rearranged to fructose-1,6-bisphosphate.
  • 2 ATP molecules are consumed.
  • Key enzymes:
  • Hexokinase/Glucokinase – Glucose → Glucose-6-phosphate
  • Phosphofructokinase-1 (PFK-1) – Fructose-6-phosphate → Fructose-1,6-bisphosphate

Stage II – Splitting Phase

  • Fructose-1,6-bisphosphate is split into two triose phosphates:
  • Glyceraldehyde-3-phosphate (G3P) and dihydroxyacetone phosphate (DHAP)
  • DHAP is converted to G3P by triose phosphate isomerase.

Stage III – Energy Yield Phase (Payoff Phase)

  • Each G3P is oxidized to pyruvate.
  • 4 ATP are produced by substrate-level phosphorylation.
  • 2 NADH + H⁺ are formed (one per G3P).
  • Key enzymes:
  • Glyceraldehyde-3-phosphate dehydrogenase – formation of NADH
  • Phosphoglycerate kinase and pyruvate kinase – substrate-level phosphorylation

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