Explain the stages of aerobic respiration that occur in the mitochondria of eukaryotes. [8]

Aerobic respiration is the controlled released of energy in cells by converting organic molecules into ATP. It invovles the reduction and oxidation of electron carriers. Firstly the link reaction occurs where pyruvate from glycolysis is converted into acetyl coenzyme A, this is done by removing CO2 from a pyruvate and reducing a NAD molecule. Next in the Krebs cycle a four carbon molecule combines with the acetyl coenzyme A and a 6 carbon molecule is formed. Next the molecule is decarboxylated twice meaning two CO2 molecules are released and a 4 carbon compound remains. 3 reduced NAD molecules and a reduced FAD molecule are formed. There is some ATP also generated during the Krebs cycle. The four carbon molecule that remains will now start the next cycle with a new acetyl coenzyme A. Next the electron transport chain occurs, the now reduced NAD and FAD molecules carry the electrons to the inner membrane of the mitochondria. The electrons are deposited to carriers which enable proton pumping to occur, protons accumulate in the inter-membrane space and generate potential energy. Through diffusion the protons now pass through the ATP synthase enzyme embedded into the membrane and using their kinetic energy create ATP by combining an ADP molecule with an extra inorganic phosphate, this process is known as chemiosmosis. Finally as the electrons travel from carrier to carrier they reach the final terminal acceptor oxygen.