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Electron Transport and Oxidative Phosphorylation It all reduces down to water.

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Presentation on theme: "Electron Transport and Oxidative Phosphorylation It all reduces down to water."— Presentation transcript:

1 Electron Transport and Oxidative Phosphorylation It all reduces down to water.

2 Mitochondria outer membrane relatively permeable inner membrane permeable only to those things with specific transporters –Impermeable to NADH and FADH 2 –Permeable to pyruvate Compartmentalization –Kreb's and β-oxidation in matrix –Glycolysis in cytosol

3 Most energy from Redox electrons during metabolic reactions sent to NAD and FAD –Glycolysis In cytosol produces 2 NADH –Pyruvate dehydrogenase reaction In mitochondrial matrix 2 NADH / glucose –Krebs In mitochondrial matrix 6 NADH and 2 FADH 2 / glucose

4 Electron Transport Chain Groups of redox proteins –On inner mitochondrial membrane –Binding sites for NADH and FADH 2 On matrix side of membrane Electrons transferred to redox proteins NADH reoxidized to NAD + FADH 2 reoxidized to FAD

5 4 Complexes proteins in specific order Transfers 2 electrons in specific order –Proteins localized in complexes Embedded in membrane Ease of electron transfer –Electrons ultimately reduce oxygen to water 2 H e - + ½ O 2 --  H 2 O

6 Electron Transport Chain

7 Complex 1 Has NADH binding site –NADH reductase activity NADH -  NAD + –NADH ---> FMN--->FeS---> ubiquinone –ubiquinone ---> ubiquinone H 2 –4 H + pumped/NADH

8 Electron Transport Chain

9 Complex II succinate ---FAD—ubiquinone –Contains coenzyme Q –FADH 2 binding site FAD reductase activity FADH 2 --  FAD

10 Electron Transport Chain

11 Complex III ubiquinone -  ubiquinone ox while cyt C gets reduced Also contains cytochromes b –proton pump 4H + Adds to gradient 8 H + / NADH 4 H + / FADH 2

12 Electron Transport Chain

13 Complex IV reduction of oxygen cytochrome oxidase cyt a+a3 red ---> oxidized state oxygen ---> water –2 H e - + ½ O 2 --  2 H 2 O –transfers e - one at a time to oxygen Pumps 2H + out –Total of 10 H + / NADH –Total of 6 H + / FADH 2

14 Totals Proton gradient created as electrons transferred to oxygen forming water 10 H + / NADH 6 H + / FADH 2

15 Electron Transport Chain

16 Generation of ATP Proton dependant ATP synthetase –Uses proton gradient to make ATP –Protons pumped through channel on enzyme From intermembrane space into matrix ~4 H + / ATP –Called chemiosmotic theory

17 Totals NADH 10 H + X 1 ATP = 2.5 ATP 4 H + FADH 2 6 H + X 1 ATP = 1.5 ATP 4 H +

18 Total ATP from mitochondrial matrix Pyruvate dehydrogenase –NADH ……………………………….2.5 ATP Krebs 3 NADH X 2.5 ATP/NADH ……….7.5 ATP FADH 2 X 1.5 ATP / FADH 2 ……….1.5 ATP GTP X 1 ATP / GTP ……………..1.0 ATP (from a separate reaction) Total…………….12.5 ATP (Per glucose = X 2 = 25 ATP)

19 What about NADH from glycolysis? NADH made in cytosol Can’t get into matrix of mitochondrion 2 mechanisms –In muscle and brain Glycerol phosphate shuttle – In liver and heart Malate / aspartate shuttle

20 Glycerol Phosphate shuttle

21 Glycerol phosphate shuttle In muscle and brain Each NADH converted to FADH 2 inside mitochondrion –FADH 2 enters later in the electron transport chain –Produces 1.5 ATP

22 Total ATP per glucose in muscle and brain Gycerol phosphate shuttle –2 NADH per glucose -  2 FADH 2 –2 FADH 2 X 1.5 ATP / FADH 2 ……….3.0 ATP –2 ATP in glycoysis……………………2.0 ATP –From pyruvate and Krebs 12.5 ATP X 2 per glucose …………… ATP Total = 30.0 ATP/ glucose

23 Malate – Aspartate Shuttle

24 Malate – Aspartate Shuttle in cytosol In liver and heart NADH oxidized while reducing oxaloacetate to malate –Malate dehydrogenase Malate crosses membrane

25 Malate – Aspartate Shuttle in matrix Malate reoxidized to oxaloacetate –Malate dehydrogenase –NAD + reduced to NADH NADH via electron transport yields 2.5 ATP Mlate – Aspartate Shuttle in cytosol

26 Total ATP per glucose in liver and heart Malate – Aspartate Shuttle –2 NADH per glucose -  2 NADH –2 NADH X 2.5 ATP / NADH…………5.0 ATP –2 ATP from glycolysis………………..2.0 ATP –From pyruvate and Krebs 12.5 ATP X 2 per glucose …………… ATP Total = 32.0 ATP/ glucose

27 Summary Total ATP / glucose –Muscle and brain30.0 ATP Uses glycerol phosphate shuttle –Heart and liver32.0 ATP Uses malate aspartate shuttle


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