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Glycolysis, Pyruvate Oxidation, and the Citric Acid Cycle

High-yield review of glycolysis, pyruvate oxidation, TCA cycle enzymes, cofactors, and net ATP/NADH yields for medical exams.

11 cards· by GuruOwl

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  1. 01
    Glycolysis occurs in the cytosol and converts one molecule of glucose into two molecules of pyruvate.
    This process occurs outside the mitochondria and does not require oxygen.
    Flashify::Medical::General::Biochemistry
  2. 02
    The rate-limiting and primary regulatory enzyme of glycolysis is phosphofructokinase-1 (PFK-1).
    It catalyzes the irreversible conversion of fructose-6-phosphate to fructose-1,6-bisphosphate.
    Flashify::Medical::General::Biochemistry
  3. 03
    PFK-1 is allosterically inhibited by ATP and citrate, and activated by AMP and fructose-2,6-bisphosphate.
    High energy signals (ATP/citrate) slow glycolysis, while low energy signals (AMP) or hormonal signals (F-2,6-BP) accelerate it.
    Flashify::Medical::General::Biochemistry
  4. 04
    The net yield per molecule of glucose in glycolysis is 2 ATP, 2 NADH, and 2 pyruvate.
    Two ATP are invested in the first phase, and four are produced in the payoff phase.
    Flashify::Medical::General::Biochemistry
  5. 05
    Pyruvate kinase is allosterically activated by fructose-1,6-bisphosphate via feed-forward regulation.
    This ensures that the products of the PFK-1 reaction trigger the final step of the pathway.
    Flashify::Medical::General::Biochemistry
  6. 06
    The pyruvate dehydrogenase complex converts pyruvate into acetyl-CoA in the mitochondria.
    This step links glycolysis to the Citric Acid Cycle and produces one NADH and one CO2 per pyruvate.
    Flashify::Medical::General::Biochemistry
  7. 07
    The rate-limiting enzyme of the Citric Acid Cycle is isocitrate dehydrogenase.
    It is inhibited by ATP and NADH and activated by ADP.
    Flashify::Medical::General::Biochemistry
  8. 08
    Succinate dehydrogenase is unique in the TCA cycle because it is also Complex II of the electron transport chain.
    It is the only TCA enzyme embedded in the inner mitochondrial membrane.
    Flashify::Medical::General::Biochemistry
  9. 09
    One turn of the Citric Acid Cycle (per acetyl-CoA) produces 3 NADH, 1 FADH2, and 1 GTP/ATP.
    Since one glucose yields two acetyl-CoA, these values double per glucose molecule.
    Flashify::Medical::General::Biochemistry
  10. 10
    The pyruvate carboxylase reaction is an example of an anaplerotic reaction that replenishes oxaloacetate.
    Anaplerotic reactions maintain the concentration of TCA cycle intermediates.
    Flashify::Medical::General::Biochemistry
  11. 11
    Under physiologic conditions, the total net ATP yield from the complete oxidation of one glucose molecule is approximately 30-32 ATP.
    This accounts for the variable ATP yield from NADH (2.5) and FADH2 (1.5).
    Flashify::Medical::General::Biochemistry