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Cell Respiration

Cell Respiration. Chapter 5. Cellular Respiration. Release of energy in biomolecules (food) and use of that energy to generate ATP ENERGY (food) + ADP + P i  ATP Two methods of breaking down food Aerobic Respiration: oxygen utilizing Anaerobic Respiration : no oxygen used.

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Cell Respiration

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  1. Cell Respiration Chapter 5

  2. Cellular Respiration • Release of energy in biomolecules (food) and use of that energy to generate ATP ENERGY (food) + ADP + Pi  ATP • Two methods of breaking down food • Aerobic Respiration: oxygen utilizing • Anaerobic Respiration: no oxygen used

  3. Aerobic Respiration • Uses oxygen in breakdown of materials and release of energy • C6H12O6 (glucose) + 6O2 6CO2 + 6H2O + Energy • Energy is released in small increments via long metabolic pathways • Allows cells to efficiently release and use energy contained in food molecules

  4. Aerobic Respiration: Overview • Glycolysis • glucose  pyruvate • Krebs Cycle • formation of electron carriers and CO2 • Oxidative Phosphorylation • electron carriers used to generate ATP

  5. Glycolysis • Occurs in cytoplasm of the cell • Breakdown of one glucose molecule into two pyruvate molecules • Yields 2 ATP molecules (net) and 2 NADH molecules Fig 5.2

  6. 2ADP 2ATP Pyruvate (3C) Pyruvate (3C) 2ADP 2ATP Glycolysis NAD+NADH Glucose (6C) 2ATP 2ADP NAD+NADH NADH = high-energy electron carrier

  7. Glycolysis • Glucose  pyruvate • 2 NAD+ + 2H+ + 4e- 2 NADH • 2 ADP + 2 Pi 2 ATP

  8. Kreb’s Cycle • Occurs in the mitochondrial matrix • Cyclical series of reactions Figs 5.7 & 5.10a

  9. Krebs Cycle:Acetyl-CoA Formation • Pyruvate transported into mitochondrial matrix • CO2 cleaved off of pyruvate, forming acetate • Acetate linked to Coenzyme A (CoA) to form acetyl-CoA • One NADH formed for each pyruvate Fig 5.6

  10. Krebs Cycle (The Cycle Itself) • Acetyl-CoA (2C) linked to oxaloacetic acid (4C), to form citric acid (6C) • Citric acid ultimately converted into oxaloacetic acid + 2CO2 • 1 GTP, 3 NADH and 1 FADH per each acetyl-CoA Fig 5.8

  11. CO2 NAD+NADH Acetyl-CoA (2C) CO2 Oxaloacetate (4C) CO2 Krebs Cycle Citrate (6C) Pyruvate (3C) 3NAD+3NADH FAD+FADH2 GDP GTP FADH2 – high energy electron carrier GTP – similar to ATP, can be converted to ATP

  12. Krebs Cycle • 3 CO2, 1 GTP, 4 NADH and 1 FADH2 produced for each pyruvate molecule. • Total: 6CO2, 2 GTP, 8 NADH, 2FADH2

  13. Oxidative Phosphorylation • Occurs across the inner mitochondrial membrane • Electrons from NADH and FADH2 are transported along an electron transport chain • Energy released used to produce ATP Fig 5.10a

  14. Oxidative Phosphorylation • H+ pumped from inside the membrane to the outside • forms [H+] gradient (more outside than inside) • H+ flows back in through ATP synthase • generates ATP • Electrons and H+ received by O2 • forms H2O Fig 5.10b

  15. Overall Reaction for Aerobic Respiration C6H12O6 + 6O2 6CO2 + 6H2O

  16. How Much ATP is Produced Per Glucose Molecule? Glycolysis 2 ATP Krebs Cycle (2 GTP) 2 ATP Oxidative Phosphorylation 26 ATP TOTAL30 ATP

  17. Triglyceride Catabolism Figs 5.11 & 5.13 • Fatty acids are converted into acetyl-CoA • Large amounts of ATP produced per fatty acid

  18. Amino Acid Catabolism Fig 5.16 Different amino acids can be converted into various Krebs Cycle intermediates

  19. Anaerobic Respiration • Produce ATP in the absence of O2 • Used regularly by skeletal muscle fibers and RBCs • Two steps: • Glycolysis - produce ATP • Lactate Formation – regenerate NAD+

  20. Glycolysis in Anaerobiosis • Glucose  Pyruvate • Net 2 ATP produced • NAD+ NADH • Need NAD+ to drive glycolysis! Fig 5.2

  21. Lactate Formation • Pyruvate  Lactate • NADH  NAD+ • Glycolysis can continue Fig 5.3

  22. How Much ATP is Produced Per Glucose Molecule? Glycolysis 2 ATP TOTAL2 ATP • Most of the energy from glucose is still present in the lactate • Lactate accumulation leads to  pH

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