Lec 9 Cellular Respiration (II) 1-6

Lec 9 Cellular Respiration (II) 1-6 - Glycolysis Harvests...

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1 Biol 113 AU2011 Lecture 9 Cellular Respiration (II) E. The citric acid cycle completes the energy-yielding oxidation of organic molecules F. During oxidative phosphorylation, chemiosmosis couples electron transport to ATP synthesis G. Fermentation and anaerobic respiration enable cells to produce ATP without the use of oxygen H. Glycolysis and the citric acid cycle connect to many other metabolic pathways I. Regulation of cellular respiration via feedback mechanisms Energy investment phase Glucose 2 ADP + 2 P 2 ATP used formed 4 ATP Energy payoff phase 4 ADP + 4 P 2 NAD + + 4 e + 4 H + 2 NADH + 2 H + 2 Pyruvate + 2 H 2 O 2 Pyruvate + 2 H 2 O Glucose Net 4 ATP formed – 2 ATP used 2 ATP 2 NAD + + 4 e + 4 H + 2 NADH + 2 H + Fig. 9.8 Glycolysis Harvests Chemical Energy by Oxidizing Glucose to Pyruvate Glycolysis (“splitting of sugar”) breaks down glucose into two molecules of pyruvate Glycolysis occurs in the cytoplasm and has two major phases: Energy investment phase Energy payoff phase E. The Citric Acid Cycle Completes the Energy- Yielding Oxidation of Organic Molecules In the presence of O 2 , pyruvate enters the mitochondrion Before the citric acid cycle can begin, pyruvate must be converted to acetyl CoA , which links the cycle to glycolysis Pyruvate Transport protein CYTOSOL MITOCHONDRION CO 2 Coenzyme A NAD + + H + NADH Acetyl CoA 1 2 3 Fig. 9.10 Fig. 9.12 The citric acid cycle has 8 steps, each catalyzed by a specific enzyme The acetyl group of acetyl CoA joins the cycle by combining with oxaloacetate, forming citrate The next 7 steps decompose the citrate back to oxaloacetate, making the process a cycle The NADH and FADH 2 produced by the cycle relay electrons extracted from food to the electron transport chain Peter v. Sengbusch, University of Hamburg, Germany Decrease in free energy ( Δ G) during glycolysis and respiration - - - NADH NAD + 2 FADH 2 2 FAD Multiprotein complexes FAD Fe•S FMN Fe•S Q Fe•S Ι Cyt b ΙΙ ΙΙΙ Cyt c 1 Cyt c Cyt a Cyt a 3 IV Free energy ( G ) relative to O 2 (kcal/mol) 50 40 30 20 10 2 (from NADH or FADH 2 ) 0 2 H + + 1 / 2 O 2 H 2 O e e e F. During Oxidative Phosphorylation, Chemiosmosis Couples Electron Transport to ATP Synthesis Fol owing glycolysis and the citric acid cycle, NADH and FADH 2 account for most of the
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This note was uploaded on 01/05/2012 for the course BIO 113 taught by Professor Swenson during the Fall '08 term at Ohio State.

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Lec 9 Cellular Respiration (II) 1-6 - Glycolysis Harvests...

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