1. Glycolysis:
* Occurs in the cytoplasm.
* Glucose is broken down into two molecules of pyruvate.
* Produces a net gain of 2 ATP and 2 NADH.
2. Transition Reaction:
* Occurs in the mitochondrial matrix.
* Pyruvate is converted into acetyl-CoA.
* Produces 1 NADH per pyruvate molecule.
3. Krebs Cycle (Citric Acid Cycle):
* Occurs in the mitochondrial matrix.
* Acetyl-CoA enters the cycle and is oxidized.
* Produces 3 NADH, 1 FADH2, and 1 ATP per acetyl-CoA molecule.
4. Electron Transport Chain (ETC):
* Occurs in the inner mitochondrial membrane.
* Electrons from NADH and FADH2 are passed down a chain of protein complexes.
* This process generates a proton gradient across the membrane, which drives the production of ATP by ATP synthase.
* Produces the majority of ATP (around 34 ATP molecules per glucose molecule).
Here's a simplified breakdown:
* Glucose (6-carbon sugar) is broken down into pyruvate (3-carbon molecule).
* Pyruvate is converted into acetyl-CoA.
* Acetyl-CoA enters the Krebs Cycle, where it is oxidized to produce energy carriers (NADH and FADH2).
* NADH and FADH2 donate their electrons to the Electron Transport Chain, generating a proton gradient.
* The proton gradient drives ATP synthesis by ATP synthase.
Overall, cellular respiration yields a net gain of about 38 ATP molecules per glucose molecule.
Note: This is a simplified explanation. The process is much more complex and involves many different enzymes and intermediates.
