Oxidative Phosphorylation & Fermentation

Summary of Glycolysis, Link and KC

Energy Accounting By the end of Glycolysis, link and Krebs cycle, how many of the original 6 carbons have been converted to CO2? All of them How many ATP’s have been made 4 ATP’s So where is the rest of the energy that was originally in the glucose? 10 NADH’s 2 FADH2

So far the ATP’s have been generated via substrate level phosphorylation Now it’s time for chemiosmosis Where is the energy Coming from for the active transport? ???

What pulls electrons out of the chain? What happens to the energy that is lost from the electrons? AHH, the active transport!

Protein complex of electron carriers Figure 9.15 H H H Protein complex of electron carriers H Cyt c IV Q III I ATP synth- ase II 2 H + 1/2O2 H2O FADH2 FAD Figure 9.15 Chemiosmosis couples the electron transport chain to ATP synthesis. NAD NADH ADP  P i ATP (carrying electrons from food) H 1 Electron transport chain 2 Chemiosmosis Oxidative phosphorylation

EFFECIENCY OF ATP PRODUCTION FOR EVERY NADH ~ 2.5 ATP’S ARE MADE FOR EVERY FADH2 ~ 1.5 ATP’S ARE MADE 10 x 2.5 = 25 ATP’s 2 x 1.5 = 3 ATP 28 ATP’s from Oxidative Phosphorylation 4 from Substrate Level Phosphorylation What is the efficiency if glucose’s ΔG = -686 kcal/mol, and ATP’s ΔG = -7.3 kcal/mol? 233.6/686 x 100 = 34%

Oxidative phosphorylation: electron transport and chemiosmosis Figure 9.16 Electron shuttles span membrane MITOCHONDRION 2 NADH or 2 FADH2 2 NADH 2 NADH 6 NADH 2 FADH2 Oxidative phosphorylation: electron transport and chemiosmosis Glycolysis Pyruvate oxidation Citric acid cycle Glucose 2 Pyruvate 2 Acetyl CoA Figure 9.16 ATP yield per molecule of glucose at each stage of cellular respiration.  2 ATP  2 ATP  about 26 or 28 ATP About 30 or 32 ATP Maximum per glucose: CYTOSOL

Oxidizing Agents NAD+ What is the oxidizing agent of glycolysis? What is the oxidizing agent of the citric acid cycle/Krebs Cycle? What is the oxidizing agent of the link reaction? How is NAD+ obtained to run all of these reactions? Oxidation of NADH and FADH2 via ETC Without oxygen what happens to the regeneration of these molecules? NAD+ GLYCOLYSIS LINK, KC ETC

Without O2 mitochondrial reactions shut down Figure 9.13 NADH 50 2 e NAD Without O2 mitochondrial reactions shut down FADH2 2 e FAD Multiprotein complexes I 40 FMN II FeS FeS Q III Cyt b 30 FeS Cyt c1 IV Free energy (G) relative to O2 (kcal/mol) Cyt c Cyt a How can Glycolysis continue without O2? Cyt a3 20 Figure 9.13 Free-energy change during electron transport. 10 2 e (originally from NADH or FADH2) 2 H + 1/2 O2 H2O

What has more potential/chemical energy pyruvate or lactate ? Figure 9.17 2 ADP  2 P i 2 ATP 2 ADP  2 P i 2 ATP Glucose Glycolysis Glucose Glycolysis 2 Pyruvate 2 NAD  2 NADH 2 CO2 2 NAD  2 NADH  2 H  2 H 2 Pyruvate Figure 9.17 Fermentation. 2 Ethanol 2 Acetaldehyde 2 Lactate (a) Alcohol fermentation (b) Lactic acid fermentation What has more potential/chemical energy pyruvate or lactate ?

Ethanol, lactate, or other products Figure 9.18 Glucose Glycolysis CYTOSOL Pyruvate No O2 present: Fermentation O2 present: Aerobic cellular respiration MITOCHONDRION Ethanol, lactate, or other products Acetyl CoA Figure 9.18 Pyruvate as a key juncture in catabolism. Citric acid cycle

Oxidative phosphorylation Figure 9.19 Proteins Carbohydrates Fats Amino acids Sugars Glycerol Fatty acids Glycolysis Glucose Glyceraldehyde 3- P NH3 Pyruvate Acetyl CoA Figure 9.19 The catabolism of various molecules from food. Citric acid cycle Oxidative phosphorylation

Oxidative phosphorylation Figure 9.20 Glucose AMP Glycolysis Fructose 6-phosphate Stimulates  Phosphofructokinase   Fructose 1,6-bisphosphate Inhibits Inhibits What would be a good allosteric/competitive inhibitor? Pyruvate ATP Citrate Acetyl CoA Figure 9.20 The control of cellular respiration. Citric acid cycle Oxidative phosphorylation

This graph shows the pH difference across the inner mitochondrial membrane over time in an actively respiring cell. At the time indicated by the vertical arrow, a metabolic poison is added that specifically and completely inhibits all function of mitochondrial ATP synthase. Draw what you would expect to see for the rest of the graphed line.