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The Citric Acid Cycle definitions

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  • Oxaloacetate
    A four-carbon molecule regenerated at the end of the cycle, enabling continuous processing of acetyl groups.
  • Acetyl CoA
    A two-carbon molecule that enters the cycle, combining with oxaloacetate to initiate citrate formation.
  • Citrate
    A six-carbon intermediate formed from acetyl CoA and oxaloacetate, marking the start of the cycle.
  • Isocitrate
    A structural isomer of citrate, featuring a secondary alcohol, primed for oxidation and decarboxylation.
  • Alpha Ketoglutarate
    A five-carbon intermediate produced after isocitrate oxidation and decarboxylation, precursor to succinyl CoA.
  • Succinyl CoA
    A four-carbon thioester intermediate, formed after a second decarboxylation, ready for hydrolysis to succinate.
  • Succinate
    A four-carbon dicarboxylate generated from succinyl CoA, later oxidized to fumarate.
  • Fumarate
    A planar, four-carbon molecule produced by succinate dehydrogenation, precursor to malate.
  • Malate
    A four-carbon alcohol formed by hydration of fumarate, oxidized in the final step to regenerate oxaloacetate.
  • NADH
    A high-energy electron carrier generated during oxidation steps, crucial for ATP production in the electron transport chain.
  • FADH2
    A reduced electron carrier formed during succinate oxidation, contributing electrons to the respiratory chain.
  • ATP
    A universal energy currency synthesized during the cycle via substrate-level phosphorylation from succinyl CoA hydrolysis.
  • Decarboxylation
    A reaction type in the cycle where a carbon atom is released as carbon dioxide, reducing the carbon count of intermediates.
  • Hydrolysis
    A reaction involving water to cleave chemical bonds, notably converting succinyl CoA to succinate and generating ATP.
  • Dehydrogenation
    A process where hydrogen atoms are removed from a substrate, often coupled with reduction of NAD+ or FAD.