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Cellular Respiration

Cellular Respiration. Energy Conversion. Why?. Convert energy to forms usable by cells Chemical bond energy  ATP energy ATP via chemiosmosis; NADH via redox reaction Electron transport Electrochemical proton concentration gradient Have store of ATP & NADH molecules available

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Cellular Respiration

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  1. Cellular Respiration Energy Conversion

  2. Why? • Convert energy to forms usable by cells • Chemical bond energy  ATP energy • ATP via chemiosmosis; NADH via redox reaction • Electron transport • Electrochemical proton concentration gradient • Have store of ATP & NADH molecules available • Drive cellular processes • Transportation of metabolites, organelles, etc… • Locomotion of cell • Synthesizing complex molecules

  3. ATP = adenosine triphosphate • Adenosine • Adenine = nitrogenous purine base • Ribose = a cyclic 5-carbon sugar • Triphosphate • Phosphate is negatively charged polyatomic ion • Placing phosphates near each other requires work • Energy of electrostatic repulsion is stored in bond • Broken bond releases energy for doing work

  4. Who? • Aerobic bacteria • All aerobic eukaryotic organisms • 1000 to 2000 mitochondria in each liver cell • Mitochondria associated with microtubules • May move in cytoplasm or be fixed in location • Concentrated in areas of high energy demands • Form long chains with each other • Wrapped around flagellum • Packed between cardiac myofibrils

  5. Where? • Mitochondrion is site of oxidative respiration • Mitochondria have double membranes • Inner vs. outer membrane • Outer membrane has transport proteins & large pores • Inner membrane is selectively permeable; forms cristae • Membranes create 2 internal compartments • Matrix is inside organelle • Enzyme-rich mixture, mDNA, ribosomes, tRNA, etc… • Intermembrane space is between membranes. • Site of ATP synthesis

  6. When? • Begins when large amounts of acetyl coenzyme A (acetyl CoA)are produced in the matrix space • Major fuel is acetyl CoA from pyruvate usually • Stores of fatty acids & glycogen fuel process • Fats are stored in adipose tissue (fuel for 1 month) • Glycogen/ glucose is stored in liver (fuel for 1 day) • Glucose via glycolysis yields pyruvate

  7. When else? • Fats can be broken down into fatty acids and glycerol • Glycerol broken down in glycolysis to pyruvate • Fatty acids broken down into 2-C fragment • Proteins can be broken down into amino acids • Certain amino acids can lose NH3 to form pyruvate • Some amino acids minus NH3 form 2-C fragment • Pyruvate/2-C fragment (acetyl CoA) enters mitochondria for citric acid cycle

  8. How? • Glycolysis • Sugar is broken down into pyruvic acid + 2 ATP • Citric acid cycle (Kreb’s cycle) • Acetyl CoAfrom pyruvate enters cycle • H2O supplies extra O2 & H+ • 2 CO2 + 2 NADH + FADH2 + 2 GTP exit • Electron transport chain • Electrons from NADH move down chain • 26 ATP formed via ATP synthase

  9. Anaerobic: Step 1 • Glycolysis • C6H12O6 2 C3H3O3- + 2 ATP + 2 NADH (net) • Glucose via 9 steps is broken down into 2 pyruvates • 3-C Pyruvate  2-C acetyl CoA + CO2

  10. Citric Acid Cycle: Step 2 • Citric acid cycle (Kreb’s cycle) in matrix • Pyruvate  Acetyl CoA+ CO2 + NADH • Acetyl CoAenters Kreb’s cycle • Kreb’s has 8 enzymatic reactions that harvest electrons • NAD+ accepts electrons  NADH carries electrons • CO2 + electrons (NADH + FADH2) + 2 ATP & H+ movement are end products

  11. Electron Transport Chain • Oxidative phosphorylation • In inner mitochondrial membrane • Electrons are delivered by NADH • Electrons move down chain of proteins • H+ build up in mitochondrial intermembrane space due to movement of electrons • ATP synthase is powered by H+ movement across membrane • 26 ATP are produced • ½ O2 + 2 H+  H2O {oxygen is final electron acceptor)

  12. Final Count • Glucose + oxygen  carbon dioxide + water + 38 ATP

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