Electron Transport and Chemiosmosis The Production of ATP

Krebs Cycle Revisited The following are produced for every TWO Acetyl-CoA molecules that enter  equivalent to 1 glucose: 4 CO2 molecules (waste) 6 NADH molecules (energy carriers) 2 FADH2 molecules (energy carriers) 2 ATP molecules (energy storage)

Overview 32-34 ATP 2 ATP 2 ATP

Electron Transport Chain NADH and FADH2 eventually carry the hydrogen atom electrons they have to a series of compounds, mainly proteins, which are on the inner mitochondrial membrane These components are arranged in order of increasing electronegativity (strongest electron acceptor is last) Electrons shuttle through the ETC like a baton handed from runner to runner in a relay race As electrons move through the ETC, their free energy is used to pump H+ ions across the membrane, generating a proton gradient which is then used to create molecules of ATP

The Details The process begins with NADH passing its two electrons to the 1st protein complex in the electron transport chain, NADH dehydrogenase The mobile electron carrier, Q , shuttles the electrons to the cytochrome b-c1 complex, then to cytochrome c, which shuttles the electrons to the last protein complex, cytochrome oxidase The enzyme cytochrome oxidase catalyzes the reaction between the electrons, protons and oxygen to form water

Electron Transfers The NADH made from glycolysis can’t pass through the inner membrane into the matrix  a glycerol – phosphate shuttle transfers the electrons from NADH to FAD+, forming FADH2 While NADH transfers its two electrons to NADH dehydrogenase first, FADH2 transfers its electrons to ubiquinone (Q) first Every time electrons pass through the major complexes in the membrane, one H+ ion is pumped into the inter- membrane space, generating a proton gradient Therefore, 3H+ ions are pumped for every NADH oxidized, and 2H+ for every FADH2

Chemiosmosis The protons that accumulate in the inter- membrane space generate a proton gradient One molecule of ATP is made when a hydrogen ion passes through the ATP synthase enzyme from the intermembrane space to the matrix  1H+ : 1ATP made ADP + Pi  ATP 32 – 34 ATP are made in this stage

Putting it All Together

Products of Cellular Respiration