Electron Transport Chain (ETC) – Simplified Explanation

The Electron Transport Chain (ETC) is the final stage of cellular respiration, occurring in the inner mitochondrial membrane . It is responsible for producing ATP, the energy currency of the cell.

Steps of ETC:

1. Electron Donation: NADH and FADH2 (from glycolysis & Krebs cycle) donate electrons to the ETC.

2. Electron Transfer: Electrons move through a series of protein complexes ( Complex I to IV ), releasing energy.

3. Proton Pumping: This energy is used to pump H+ ions (protons) from the mitochondrial matrix to the intermembrane space, creating a proton gradient.

4. ATP Formation: Protons flow back into the matrix through ATP synthase , driving the formation of ATP from ADP + P.

5. Oxygen as Final Acceptor: At Complex IV , electrons combine with oxygen (O2) and protons to form water (H2O).

Conclusion:

The ETC produces around 34 ATP per glucose molecule, making it the most efficient energy-producing process in cells. Oxygen plays a vital role as the final electron acceptor.