Electron Transport Chain Oxidative Phosphorylation Almoeiz Yousif 2

Electron Transport Chain & Oxidative Phosphorylation Almoeiz Yousif

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What’s the point of oxidizing food? ATP The Point is to Make ATP! Monday, November 30, 2020 Almoeiz Yousif 3

When oxidizing food, the reduced coenzymes NADH and FADH 2 are produced. • NAD+ + 2 e- + 2 H+ → NADH + H+ • FAD + 2 e- + 2 H+ → FADH 2 Monday, November 30, 2020 Almoeiz Yousif 4

NADH 5

Oxidizing glucose • NADH is produced from glycolysis • NADH is produced from converting pyruvate to acetyl Co. A • NADH and FADH 2 are produced from citric acid cycle • These CAN be used to produce ATP! Monday, November 30, 2020 Almoeiz Yousif 6

Definition of Oxidative Phosphorylation Process by which ATP is formed by oxidizing NADH or FADH 2 7

1. ELECTRON TRANSPORT CHAIN (NADH → NAD) 2. OXIDATIVE PHOSPHORYLATION ( ADP → ATP) ATP synthesis Monday, November 30, 2020 Almoeiz Yousif 8

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General properties • Takes place in the inner mitochondrial membrane • Only in presence of O 2 (aerobic) • Produces LOTS of ATPs. yields ~34 ATP from 1 glucose! Monday, November 30, 2020 Almoeiz Yousif 10

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Electron Transport Chain Four complexes found on the inner mitochondrial membrane. • Complexes I, III, IV • Complexes I, II and IV are embedded within membrane. They are all fixed. 12

Ubiquinone is lipid-soluble, so it is found inside membrane. cytochrome c is water-soluble, found above membrane. Ubiquinone and cytochrome c are mobile. Monday, November 30, 2020 Almoeiz Yousif 13

Mitochondrial Electron Transport Chains Very similar to standard bacterial aerobic respiration chains 14

Complex I • NADH dehydrogenase • Transfers e- from NADH to Ubiquinone. Monday, November 30, 2020 15

Complex II • Succinate dehydrogenase • Transfers e- from FADH 2 to Ubiquinone 16

Complex III • Cytochrome c reductase. • Transfers e- from Ubiquinone to cytochrome c.

Complex IV • Cytochrome c oxidase • Transfers e- from cytochrome c to O 2. ½ O 2 + 2 H + + 2 e- H 2 O

functions of each of 4 complexes • complex I- accepts electrons from NADH, passes to: • Complex II- accepts electrons from FADH 2 and then passes to: • Complex III- accepts electrons from I and II, passes to: • Complex IV- accepts electrons from III and transfers them to oxygen Monday, November 30, 2020 Almoeiz Yousif 19

What is ETC ? It is the final common pathway by which electrons derived from NADH and FADH 2 of the body flow to oxygen. 2 H+ + ½ O 2 +2 e- Monday, November 30, 2020 Almoeiz Yousif H 2 O 20

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ATP from Glucose For the complete oxidation of 1 glucose molecule Glycolysis 8 ATP 2 Pyruvate to 2 Acetyl Co. A 6 ATP 2 Acetyl Co. A to 4 CO 2 24 ATP Glucose + 6 O 2 6 CO 2 + 6 H 2 O + 38 ATP Monday, November 30, 2020 Almoeiz Yousif 23

INHIBITORS • Inhibitors of electron transport chain • Inhibitors of oxidative phosphorylation • Uncouplers of oxidative phosphorylation Monday, November 30, 2020 Almoeiz Yousif 24

Inhibitors of oxidative phosphorylation u. Blocking. The antibiotic oligomycin blocks the flow of H+ directly inhibiting ATP synthesis. Monday, November 30, 2020 Almoeiz Yousif 25

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Uncouplers An uncoupling protein is a mitochondrial inner membrane protein that can dissipate the proton gradient before it can be used to provide the energy for oxidative phosphorylation Monday, November 30, 2020 27

Uncouplers • Does uncoupling serve any useful purpose? – body heat generation Monday, November 30, 2020 Almoeiz Yousif 28

Uncoupled e- Transport & Heat • Nonshivering thermogenesis An uncoupling protein (thermogenin) is produced in brown adipose tissue of newborn mammals and hibernating mammals. This protein of the inner mitochondrial membrane functions as a H+carrier. – Energy from ETC is released as heat. http: //www. trudicanavan. com/b-baby. jpg