What Is The Electron Transport Chain (etc)

The Electron Transport Chain (ETC) is a feared topic in A-Level Biology, but here is a detailed breakdown. You should have already covered this topic and this explanation is for revision. ;

To begin, we must first understand that the main purpose of Glycolysis, Link Reaction and Kreb`s Cycle leading up to the ETC, is to strip biochemical molecules of their Hydrogens and deliver them to the ETC using NADH which carries the Hydrogens to the ETC like a bus.

At the ETC, NADH delivers Hydrogen in the from of Hydrogen ion (H+) and electrons. The electrons are passed onto the ETC directly and as they are passed from protein complex 1 to protein complex 4, they provide the energy needed for the Protein complexes to pump H+ from the matrix to intermembrane space of the Mitochondria. This creates a chemiosmotic gradient.

Finally, the H+ move down this chemiosmotic concentration gradient via diffusion through the final protein complex 5 (ATP synthase) and the movement of H+ through the ATP synthase is converted into chemical energy and forming a bond between ADP + Pi to make ATP.