1.4.6 Oxidative phosphorylation and chemiosmosis
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- Created on: 21-04-16 14:56
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- Oxidative phosphorylation an chemiosmosis
- The final stage of aerobic respiration.
- Involves electron carriers embedded in the inner mitochondrial matrix which are folded into cristae.
- Reduced NAD and FAD are reoxidised when they donate hydrogen atoms to the electron carriers.
- The hydrogen atoms are split into protons and electrons.
- The first electron carrier to accept electrons from reduced NAD is a protein complex (complex I) called NADH
- The protons into solution in the matrix.
- Electron transport chain
- Electrons are passed along a chain of electron carriers then donated to molecular oxygen, the final electron acceptor.
- Chemiosmosis
- As electrons flow along the chain, energy is released.
- It is used by coenzymes associated with complexes I, III and IV to pump protons across to the intermembrane space.
- This builds up a proton gradient which is also a pH gradient and an electrochemical gradient.
- Potential energy builds up in the intermembrane space.
- The hydrogen ions can diffuse through ion channels in the membrane
- The flow of hydrogen ions is chemiosmosis
- The hydrogen ions can diffuse through ion channels in the membrane
- Potential energy builds up in the intermembrane space.
- This builds up a proton gradient which is also a pH gradient and an electrochemical gradient.
- It is used by coenzymes associated with complexes I, III and IV to pump protons across to the intermembrane space.
- As electrons flow along the chain, energy is released.
- Oxidative phosphorylation
- The formation of ATP by the addition of inorganic phosphate to ADP in the presence of oxygen
- As protons flow through an ATP synthase enzyme, they drive the rotation of part of the enzyme.
- This joins ADP and P to make ATP.
- The electrons are passed on to molecular oxygen- the final electron acceptor.
- Hydrogen ions also join so that the oxygen is reduced to water.
- The electrons are passed on to molecular oxygen- the final electron acceptor.
- This joins ADP and P to make ATP.
- As protons flow through an ATP synthase enzyme, they drive the rotation of part of the enzyme.
- How much ATP is made?
- 10 NAD can produce 26 ATP during oxidative phosphorylation
- With ATP made during glycolysis and the Krebs cycle the total yeild of ATP per molecule of glucose respired should be 30 molecules.
- This is rarely achieved due several reasons.
- Proton leak across the mitochondrial membrane.
- Some ATP produced is used to actively transport pyruvate over the membrane
- Some ATP is used for the shuttle to bring hydrogen from reduced NAD from glycolysis into the mitochondria.
- This is rarely achieved due several reasons.
- With ATP made during glycolysis and the Krebs cycle the total yeild of ATP per molecule of glucose respired should be 30 molecules.
- 10 NAD can produce 26 ATP during oxidative phosphorylation
- The formation of ATP by the addition of inorganic phosphate to ADP in the presence of oxygen
- The final stage of aerobic respiration.
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