Explain the role of the coenzymes NADH and FADH2 in oxidative phosphorylation and why it is significant. (6 marks)

NADH and FADH2 oxidised to NAD and FAD in the marix by electron carrier proteins in the inter mitochondrial membrane.This liberates H+ ions and excites electrons which pass down the electron tansport chain (ETC).The excited electrons' energy is used to actively transport H+ ions across the inter mitochondrial membrane into the intermembrane space so the concentration of H+ ions is higher in the intermembrane space than in the matrix.Chemiosmosis of H+ ions through ATP synthase produces ATP from ADP and a lone phosphate group.At the end of the ETC, the electrons react with H+ ions and Oxygen to form water; 2H+ + 2e- + 1/2O2 = H2O.The coenzymes NAD and FAD are then reduced again in gylcolysis and the Kreb's Cycle therefore acting as proton transporters.