Glycolysis, Pyruvate Oxidation and Kreb’s have produced very little ATP and some energy in the form of electron carriers Majority of ATP will come from oxidative phosphorylation Occurs on the inner mitochondrial membrane

ELECTRON TRANSPORT CHAIN: a series of electron carriers and proteins that are embedded in the inner mitochondrial membrane Electrons from NADH and FADH 2 are transported through the chain and provide the energy needed for oxidative phosphorylation

ELECTRON CARRIERS NAD+ accepts 2 electrons and 1 H+ FAD accepts 2 electrons and 2 H+ These electrons will be passed along to the electron acceptors in the ETC - Electrons are passed one at a time in a series of redox reactions - As electrons move from complex to complex, they become more stable - H+ remain in solution in the matrix

Three major electron carriers: - NADH dehydrogenase - bc 1 complex - Cytochrome oxidase complex *** 2 Electrons from each NADH pass through all three carriers and cause 3 H+ to be pumped to the intermembrane space *** Electrons from FADH 2 only pass to Q then through bc 1 and cytochrome oxidase complex causing 2 H+ to be pumped to the intermembrane space

Electrons are passed through the electron carriers until they reach the final electron acceptor, oxygen - Each oxygen combines with two electrons and two hydrogen ions to form a water molecule

Each of these complexes use energy from the passing of electrons to actively transport H+ out of the matrix to the intermembrane space - Creates a hydrogen ion gradient across the membrane

The energy from NADH and FADH 2 creates an electrochemical gradient – the hydrogen ion gradient - The inner mitochondrial membrane restricts the passage of H+ along their gradient - As the gradient increases, it gains [H+] in the intermembrane space, this electrical potential energy is converted into chemical potential energy by ATP synthases

CHEMIOSMOSIS: When electrons move down their gradient through an ATP synthase complex, the energy used to phorphorylate ADP to form ATP

Factors to consider: - 1 NADH forms 3 ATP - 1 FADH 2 forms 2 ATP - The mitochondrial membrane is impermeable to NADH thus the NADH from glycolysis must be delivered by a NAD+ in the mitochondrion or by a FADH in the mitochondrion (this requires energy)

Eukaryotes can form a total of 36 ATP per glucose Prokaryotes can form a total of 38 ATP per glucose

NET ATP PRODUCTION NET NADH PRODUCTION NET FADH 2 PRODUCTION GLYCOLYSIS22 (turned into 2 FADH 2) 0 PYRUVATE OXIDATION 020 KREBS CYCLE262 ELECTRON TRANSPORT CHAIN 4 + (8x3) + (4x2) = = 36 * 34 if 2 ATP are used to transport NADH from glycolysis * Assuming NADH becomes FADH (10x3) + (2x2) = = 38 * 34 if 2 ATP are used to transport NADH from glycolysis * Assuming NADH becomes NADH

Factors that can lower ATP count - H+ leak through inner mitochondrial membrane (not pass through ATP synthase) - Energy from H+ gradient is used to transport pyruvate from glycolysis into mitochondria - Energy is used to transport ATP out of mitochondria ** Experimentally measured values ~ ATP per glucose