• Two ATP's used to generate one molecule of glucose (6C)
  • ATP donates phosphate to glucose to form activated glucose
  • Activated glucose is then converted to two molecules of triose phosphate (3 Carbon Molecule)
  • Triose phosphate donates hydrogen (oxidised) to NAD (2 molecules of reduced NAD is produced)
  • 2 molecules of pyruvate is also made.
  • During the conversion of triose phosphate to pyruvate, energy is released to convert 4 ADP molecules into 4 ATP molecules.


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Link reaction

  • Pyruvate produced from glycolysis are actively transported into the MATRIX of the mitochondia:
  • Pyruvate oxidised by removing hydrogen- taken up by NAD to form NADH (reduced NAD)
  • Pyruvate loses a carbon atom and CARBON DIOXIDE is formed.
  • Acetyl group combines with COENZYME A to form ACETYLCOEZYME A.

2pyruvate+ 2NAD+ 2CoA→2acetyl CoA+ 2NADH+ 2CO2


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The Krebs Cycle

  • Acetyl CoA (2C) reacts with oxaloacetate (4C) to form citrate (6C)
  • Citrate loses C and CO2 is formed and loses a H proton to reduce NAD into NADH.
  • alpha-ketoglutarate is formed (5C)
  • It loses a C and CO2 is formed.
  • Oxaloacetate is regenerated (4C):
  • 2 NAD's are reduced
  • 1 FAD is reduced.
  • ATP is produced from substrate-level phosphorylation.


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  • NADH and FADH binds with the proton pumps- releases protons (hydrogen is a proton m8) and electrons.
  • Energy released from electrons causes hydrogen ions (protons) to be actively transported to into the intermembrane space. The enegy being released causes this to happen along the electron chain.
  • At the end of the chain, electrons combine with protons and oxygen to form water (H2O).
  • Therefore, oxygen is named the final electron acceptor.


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Anaerobic Respiration

  • Glucose is converted to pyruvate by glycolysis.
  • 2 ATP for 1 Glucose (instead of 36 ATP for 1 glucose in aerobic resp.)
  • ATP only produced by substrate-level phosphorylation during glycolysis.
  • Electrons released by NADH and cannot be transported down the ETC because final electron acceptor is absent.
  • NADH is oxidised to form either lactate or ethanol- enough NAD is regenerated so glycolysis can continue.
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