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Complex Organic Molecules Catabolic pathways Energy ENERGY For work Lost as heat Simpler waste Products w/ Less Energy Example is Cellular Respiration “oxidation of glucose” ?????? Lose electrons = Oxidized (LEO) Gain electrons = Reduced (GER) Oxidation / Reduction reactions or Redox reactions have to occur in pairs Electrons move toward the more electronegative atoms Oxygen is most common electron acceptor -NAD+ is a coenzyme -is found in all cells -helps transfer electrons Overview of respiration -glucose is oxidized -electrons (hydrogen atoms) leave the carbon atoms and combine w/ O2 -this happens by a series of steps via NAD+ and an electron transport chain -During this process ATP is produced Two ways to get ATP 1 Oxidative phosphorylation ATP production that is coupled to the exergonic transfer of electrons from food to oxygen 2 Substrate level phosphorylation ATP production by direct enzymati transfer of phosphate from an intermediate substrate to ADP Glycolysis overview -glucose (contain 6 Carbons) is split into two 3-carbon sugars. -these 3-carbon sugars are oxidized and rearranged to form 2 pyruvate molecules -occurs in the cytosol -no CO2 released -occurs whether or not oxygen is present. -2 net ATP produced Glycolysis Animation Figure 7.UN09 Glycolysis ATP Pyruvate oxidation Citric acid cycle Oxidative phosphorylation: electron transport and chemiosmosis ATP ATP Figure 7.12 NADH Free energy (G) relative to O2 (kcal/mol) 50 2 e− NAD FADH2 40 FMN 2 e− FAD Fe•S II I Fe•S Q III Cyt b 30 Multiprotein complexes Fe•S Cyt c1 IV Cyt c Cyt a 20 10 0 Cyt a3 2 e− (originally from NADH or FADH2) 2 H ½ O2 H2O Figure 7.14 H H H Protein complex of electron carriers H Cyt c IV Q III I II FADH2 FAD NADH 2 H ½ O2 ATP synthase H2O NAD ADP P (carrying electrons from food) ATP i H 1 Electron transport chain Oxidative phosphorylation 2 Chemiosmosis Figure 7.13 H INTERMEMBRANE SPACE Stator Rotor Internal rod Catalytic knob ADP MITOCHONDRIAL MATRIX P i ATP animation http://www.sumanasinc.com/we bcontent/animations/content/atp synthase.html Figure 7.15 Electron shuttles span membrane CYTOSOL 2 NADH 6 NADH 2 NADH Glycolysis Glucose MITOCHONDRION 2 NADH or 2 FADH2 2 Pyruvate Pyruvate oxidation 2 Acetyl CoA 2 ATP Maximum per glucose: 2 FADH2 Citric acid cycle Oxidative phosphorylation: electron transport and chemiosmosis 2 ATP about 26 or 28 ATP About 30 or 32 ATP Brown Fat in hibernating animals Contain uncoupling protein that is a channel protein that allows diffusion of H+ NOT through ATP synthase Comparison of chemiosmosis in chloroplasts and mitochondria SIMILARITIES An ETC in a membrane transports protons across a membrane ATP synthase in membrane couples diffusion of protons with phosphorylation of ADP ATP synthase and electron carriers (cytochromes) are very similar in both DIFFERENCES ETC -mito transfer chemical E from food to ATP -electrons are extracted from oxidation of food molecules -chloroplasts transform light E into chemical E -uses light E to drive electrons to top of transport chain SPACIAL ORGANIZATION -mito pump protons from matrix out to the intermembrane space (which is a reservoir for protons) -chloro. Thylakoid membrane pumps protons from stroma into thylakoid compartment (serve as a proton reservoir) Fermentation