ELECTRON TRANSPORT CHAIN

OXIDATIVE PHOSPHORYLATIONGlycolysis, 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

OXIDATIVE PHOSPHORYLATION

ELECTRON TRANSPORT CHAINELECTRON TRANSPORT CHAIN: a series of electron carriers and proteins that are embedded in the inner mitochondrial membrane

Electrons from NADH and FADH2 are transported through the chain and provide the energy needed for oxidative phosphorylation

ELECTRON TRANSPORT CHAINELECTRON CARRIERSNAD+ 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

ELECTRON TRANSPORT CHAINThree major electron carriers:

- NADH dehydrogenase- bc1 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 FADH2 only pass to Q then through bc1 and cytochrome oxidase complex causing 2 H+ to be pumped to the intermembrane space

ELECTRON TRANSPORT CHAIN

ELECTRON TRANSPORT CHAINElectrons 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

ELECTRON TRANSPORT CHAIN

ELECTRON TRANSPORT CHAINEach 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

CHEMIOSMOSISThe energy from NADH and FADH2 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

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

YIELD OF ATP FROM AEROBIC RESPIRATION

Factors to consider:- 1 NADH forms 3 ATP- 1 FADH2 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)

YIELD OF ATP FROM AEROBIC RESPIRATION

Eukaryotes can form a total of 36 ATP per glucose

Prokaryotes can form a total of 38 ATP per glucose

YIELD OF ATP FROM AEROBIC RESPIRATION

NET ATP PRODUCTION

NET NADH PRODUCTION

NET FADH2 PRODUCTION

GLYCOLYSIS 2 2 (turned into 2 FADH2)

0

PYRUVATE OXIDATION

0 2 0

KREBS CYCLE 2 6 2ELECTRON TRANSPORT CHAIN

4 + (8x3) + (4x2)

= 4 + 24 + 8= 36

* 34 if 2 ATP are used to

transport NADH from glycolysis

* Assuming NADH becomes

FADH2

4 + (10x3) + (2x2)

= 4 + 30 + 4= 38

* 34 if 2 ATP are used to

transport NADH from glycolysis

* Assuming NADH becomes

NADH

YIELD OF ATP FROM AEROBIC RESPIRATION

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 ~ 30-32 ATP per glucose