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Cellular Respiration

Cellular Respiration. Obtain energy from the degradation of sugars Uses Oxygen and produces CO 2 Many steps take place in the mitochondria of cells Complementary process to photosynthesis Will recognize many of the same molecules. Oxidation-Reduction reactions.

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Cellular Respiration

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  1. Cellular Respiration • Obtain energy from the degradation of sugars • Uses Oxygen and produces CO2 • Many steps take place in the mitochondria of cells • Complementary process to photosynthesis • Will recognize many of the same molecules

  2. Oxidation-Reduction reactions • Type of reaction when an electron is transferred from one atom or molecule to another • Electron donor is reducing agent • Electron acceptor is oxidizing agent • The addition of electron to a molecule or atom is called reduction • Energy is released when electrons are transferred to lower energy state molecules • Electron transfer chains

  3. Cellular Respiration Mechanisms • 3 Stages • Glycolysis-happens in cytosol of cell • Krebs cycle-happens in matrix of mitochondria • Electron transport and oxidative phophorylation-cristae

  4. Glycolysis • Means “sugar splitting”-glucose is split into Pyruvate • First step of respiration • Broken into two stages • Energy investment phase-uses 2ATP • Energy Payoff Phase-Yields 4 ATP +2 NADH • Net of 2 ATP

  5. Energy Investment Phase • Begins with Glucose • 2 ATPs are used to phosphorylate Carbons 1 and 6 • Activated intermediates • Isomerase converts glucose to fructose structure • Isomerase is enzyme that changes one molecule to an isomer • Eventually yields 2 molecules of glyceraldehyde phosphate • Enters energy payoff phase

  6. Fig. 9-8 Energy investment phase Glucose 2 ADP + 2 2 ATP used P Energy payoff phase formed 4 ADP + 4 P 4 ATP 2 NAD+ + 4 e– + 4 H+ 2 NADH + 2 H+ 2 Pyruvate + 2 H2O Net 2 Pyruvate + 2 H2O Glucose 4 ATP formed – 2 ATP used 2 ATP 2 NAD+ + 4 e– + 4 H+ 2 NADH + 2 H+

  7. Energy Payoff Phase • Starts with Glyceraldehyde phosphate • 2 for every glucose • Enzyme adds phosphate GP while 2 NADH molecules are produces • Phosphates are eventually loss resulting in the production of 4 ATP molecules • The final product is Pyruvate • Moves into Krebs cycle

  8. Transition • Once Pyruvate enters Mitochondrion it is converted to Acetyl CoA and CO2 • Acetyl CoA is the starting molecule for the Krebs cycle

  9. Fig. 9-10 CYTOSOL MITOCHONDRION NAD+ NADH + H+ 2 1 3 Acetyl CoA Coenzyme A Pyruvate CO2 Transport protein

  10. Krebs cycle • Completes the oxidation of organic molecules • Takes place in matrix of mitochondria • Cyclic like Calvin cycle • Produces 1 ATP for each acetyl CoA • 2 per glucose • Many high energy electrons are saved as 3NADH and FADH2 per cycle • Also produces 2 CO2 molecules per cycle

  11. Fig. 9-12-8 Acetyl CoA CoA—SH NADH H2O 1 +H+ NAD+ Oxaloacetate 8 2 Malate Citrate Isocitrate NAD+ Citric acid cycle NADH 3 + H+ 7 H2O CO2 Fumarate CoA—SH -Keto- glutarate 4 6 CoA—SH 5 FADH2 CO2 NAD+ FAD Succinate NADH P i + H+ Succinyl CoA GDP GTP ADP ATP

  12. Fig. 9-11 Pyruvate CO2 NAD+ CoA NADH + H+ Acetyl CoA CoA CoA Citric acid cycle 2 CO2 FADH2 3 NAD+ NADH 3 FAD + 3 H+ ADP + P i ATP

  13. Transition 2 • NADH and FADH2 are used in the electron transport chain • Happens in cristae of mitochondrion • Uses Oxygen as ultimate electron acceptor

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