1. Glycolysis:
* During glycolysis, glucose is broken down into pyruvate.
* This process generates NADH as a byproduct, specifically two molecules of NADH per molecule of glucose.
* The electrons carried by NADH are derived from the oxidation of glucose.
2. Krebs Cycle (Citric Acid Cycle):
* Pyruvate enters the mitochondria and is converted into acetyl-CoA.
* Acetyl-CoA enters the Krebs Cycle, where it is further oxidized, generating more NADH (three molecules of NADH per acetyl-CoA).
* Again, the electrons carried by NADH are from the oxidation of the fuel molecule.
3. Electron Transport Chain:
* The NADH produced in glycolysis and the Krebs Cycle delivers its high-energy electrons to the electron transport chain located within the mitochondrial membrane.
* These electrons are passed along a series of protein complexes, releasing energy at each step.
* This energy is used to pump protons across the membrane, creating a proton gradient.
* The flow of protons back across the membrane powers the production of ATP, the cell's energy currency.
In Summary:
NADH acts as a vital link between the initial stages of glucose breakdown and the final energy-producing step in cellular respiration. It captures high-energy electrons released during glucose oxidation and delivers them to the electron transport chain, where they are used to drive ATP synthesis.
Without NADH, cellular respiration could not effectively extract energy from glucose, leaving the cell with a severely limited energy supply.
