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Citric Acid Cycle 4 definitions

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  • Fumarate
    Intermediate in the citric acid cycle converted to L-malate by addition of water, with a near-zero delta G, allowing reversibility.
  • L-malate
    Product formed from fumarate in the citric acid cycle, exists as L or D form, and is further converted to oxaloacetate.
  • Malate dehydrogenase
    Enzyme catalyzing the conversion of malate to oxaloacetate, producing NADH, with a reaction that is easily reversible.
  • Oxaloacetate
    Molecule regenerated at the end of the citric acid cycle, serving as the acceptor for acetyl CoA to restart the cycle.
  • NADH
    Electron carrier produced in the citric acid cycle, yielding 2.5 ATP per molecule during oxidative phosphorylation.
  • FADH2
    Electron carrier generated in the citric acid cycle, producing 1.5 ATP per molecule due to its metabolic entry point.
  • ATP
    Primary energy currency of the cell, with a daily turnover of about 50 kilograms, generated through glycolysis, pyruvate oxidation, and the citric acid cycle.
  • Glycolysis
    Metabolic pathway breaking down glucose, contributing 5–7 ATP to the total yield per glucose molecule.
  • Pyruvate oxidation
    Process converting pyruvate to acetyl CoA, generating NADH and contributing 5 ATP per glucose molecule.
  • Acetyl CoA
    Two-carbon molecule entering the citric acid cycle, derived from pyruvate oxidation, essential for ATP production.
  • Citrate synthase
    Enzyme catalyzing the first step of the citric acid cycle, regulated by ATP, NADH, succinyl CoA, and its product citrate.
  • Isocitrate dehydrogenase
    Key enzyme in the citric acid cycle, inhibited by ATP and stimulated by ADP, controlling cycle flux.
  • Alpha-ketoglutarate dehydrogenase
    Enzyme complex in the citric acid cycle, regulated by NADH and succinyl CoA, involved in irreversible steps.
  • Anaplerotic reactions
    Processes replenishing citric acid cycle intermediates, especially oxaloacetate, to maintain cycle function.
  • Succinyl CoA
    Intermediate in the citric acid cycle, production is irreversible and regulated, also acts as a feedback inhibitor.