Cellular energy metabolism: glycolysis, the Krebs cycle and oxidative phosphorylation
Where glycolysis, pyruvate dehydrogenase, the Krebs cycle and the electron transport chain sit, their regulated steps and vitamin cofactors, an ATP tally per glucose, and how blocks at each stage explain type A and type B lactic acidosis, thiamine deficiency, cyanide and salicylate toxicity, metformin, and Krebs enzyme mutations in cancer.
Tier 2Medical sciences concept
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- Glycolysis (cytosol) turns glucose into 2 pyruvate for a net 2 ATP and 2 NADH. It needs no oxygen, but needs NAD⁺ back, which lactate dehydrogenase supplies when oxygen is short.
- Pyruvate dehydrogenase (PDH, mitochondrial) commits pyruvate to acetyl-CoA. It needs thiamine.
- The Krebs cycle strips electrons from acetyl-CoA as NADH and FADH₂; the electron transport chain turns them into a proton gradient that drives ATP synthase.
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Sources
- Lehninger Principles of Biochemistry, 8th editionMacmillan Learning (Nelson DL, Cox MM), 2021
- Guyton and Hall Textbook of Medical Physiology, 14th editionElsevier (Hall JE, Hall ME), 2021
- Kraut JA, Madias NE. Lactic acidosis. N Engl J Med 2014;371:2309-19New England Journal of Medicine, 2014
- Gorman GS, Chinnery PF, DiMauro S et al. Mitochondrial diseases. Nat Rev Dis Primers 2016;2:16080Nature Reviews Disease Primers, 2016
- Last updated
- 14 November 2026
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