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lecture 9 biao ding

lecture 9 biao ding - Biol 113 AU2010 Lecture 9 Cellular...

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1 Biol 113 AU2010 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 Fig. 9.10 CYTOSOL MITOCHONDRION NAD + NADH + H + 2 1 3 Pyruvate Transport protein CO 2 Coenzyme A Acetyl CoA 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 Fig. 9.11 Pyruvate NAD + NADH + H + Acetyl CoA CO 2 CoA CoA CoA Citric acid cycle FADH 2 FAD CO 2 2 3 3 NAD + + 3 H + ADP + P i ATP NADH The citric acid cycle , also called the Krebs cycle , takes place within the mitochondrial matrix The cycle oxidizes organic fuel derived from pyruvate, generating 1 ATP, 3 NADH, and 1 FADH 2 per turn (FAD - Flavin adenine dinucleotide) Fig. 9.12 Acetyl CoA CoA—SH Citrate H 2 O Isocitrate NAD + NADH + H + C O 2 α -Keto- glutarate CoA—SH C O 2 NAD + NADH + H + Succinyl CoA CoA—SH Pi GTP GDP ADP ATP Succinate FAD FADH 2 Fumarate Citric acid cycle H 2 O Malate Oxaloacetate NADH 1 2 3 4 5 6 7 8 + H + NAD + The citric acid cycle has eight steps, each catalyzed by a specific enzyme The acetyl group of acetyl CoA joins the cycle by combining with oxaloacetate, forming citrate The next seven 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 Following glycolysis and the citric acid cycle, NADH and FADH 2 account for most of the
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