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Cellular Respiration

Cellular Respiration . Producing ATP from the energy in food. An Overview. ATP is immediate source of energy used by cells Energy in ATP held in phosphodiester bonds Most energy release in cells results from redox rxns. involving Glucose C 6 H 12 O 6 + O 2 --> 6 CO 2 + 6 H 2 O + energy.

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Cellular Respiration

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  1. Cellular Respiration Producing ATP from the energy in food

  2. An Overview • ATP is immediate source of energy used by cells • Energy in ATP held in phosphodiester bonds • Most energy release in cells results from redox rxns. involving Glucose • C6H12O6 + O2 --> 6 CO2 + 6 H2O + energy

  3. 40% of energy in Glucose is converted to usable energy in ATP • Production of ATP and other organic molecules is endergonic and require a constant input of energy to continue. • The source of that energy is the sun. • Photosynthesis is essentially the opposite of Cellular Respiration. • Energy flows from sun to autotrophs to heterotrophs. • All energy is lost eventually as work or heat.

  4. Cellular Respiration THE BEGINNING * GLYCOLYSIS

  5. Glycolysis • Activation of Glucose • 1 ATP used to add “P” to Glucose • forms Glucose Phosphate • Fructose Phosphate then formed • 1 ATP - P = 1 ADP + P

  6. Formation of Sugar Diphosphate • 1 ATP used to add “P” to Fructose Phosphate • Forms Sugar Diphosphate (sugar and two “P”’s) • 1 ATP - P = 1 ADP + P

  7. Formation and Oxidation of G3P • Sugar Diphosphate (6 C) into two 3 C molecules • 1 into G3P • Other 3 C becomes a different 3 C, but is then converted into G3P • Both G3P’s lose an H • Accepted by NAD to make 2 NADH’s • High energy level e-’s carried by the H’s • Some of the energy used to make 2 ATP’s

  8. Formation of Pyruvate • 3 more reactions make two Pyruvate molecules • The energy released from these reactions used to make 2 ATP’s • Two C3H4O3 = 6 C’s, 8 H’s, 6 O’s (just 4 H’s removed from Glucose, C6H12O6.

  9. Summary of Glycolysis • Glucose split into two 3 C’s • 2 ATP’s used for activation energy • 2 molecules NADH produced (+ 2 H+) • 4 ATP’s made (net gain of 2 ATP’s) • Pyruvate is the 3 C made • Will next enter Kreb’s Cycle if Oxygen is available • Will undergo fermentation if no Oxygen is available • Occurs in cytoplasm • No oxygen required (but can be present)

  10. The Oxidation of Pyruvate A necessary first step prior to either The Citric Acid Cycle or Fermentation

  11. Oxidation of Pyruvate • 2 e - and their associated H released • 1 e - from each Pyruvate • Accepted by 2 NAD’s to form 2 NADH’s • A C also released from each pyruvate • forms two CO2’s • Results in formation of two acetyl groups

  12. The Citric Acid Cycle • Occurs in mitochondria • An aerobic process • Begins with acetyl (or Pyruvate if you include the oxidation of pyruvate as part of this process) • Ends with CO2 ,H2O, NADH and FADH2 and some ATP being produced

  13. The process • Acetyl groups combine with a coenzyme • the coenzyme is CoA • just “hanging around” in mitochondria • forms AcetylCoA • AcetylCoA joins a 4C compound already present • The 4 C is oxaloacetic Acid • forms Citric Acid (6C) • Citric Acid undergoes two rxns to form isocitric acid

  14. Isocitric Acid is oxidized • The H’s released are accepted by NAD and FAD • forms 4 NADH and two FADH2 • some of the energhy used to form two more ATP molecules • Forms Fumaric Acid • Fumaric Acid undergoes 2 rxns • Forms Oxaloacetic Acid • Combines with AcetylCoA to form Citric Acid • The whole darn thing happens again! • Two more NADH’s produced

  15. 2NADH produce in the Oxidation of Pyruvate • 2ATP’s produced in Citric Acid Cycle • 6 NADH and 2 FADH2 also produced in Citric Acid Cycle • Add that to the net gain of 2 ATP and 4 NADH produced in glycolysis • 4ATP • 10 NADH • 2 FADH2

  16. Electron Transport Chain • Utilizing the energy held in NADH and FADH2 previously produced to make ATP • Produced by chemiosmosis • Gradient produced b/w the area within the inner and outer mitochondrial membrane and inside the mitochondria • 2 NADH from glycolysis were actively transported in (required 1 ATP each)

  17. The ETC • High energy e - ’s carried by NADH and FADH2 transported out of inner mitochondrial membrane into area b/w inner and outer membrane by cytochromes embedded in the membrane. • protons follow • e - accepted by Oxygen to form H2O • creates proton conc. gradient • Protons move back across membrane in response to gradient • Movement coupled to production of ATP

  18. The Balance Sheet from ETC • Each NADH drives synthesis of 3 ATP • 10 NADH from glycolysis, oxidation of pyruvate and the citric acid cycle • 30 ATP • but the NADH’s from glycolysis cost 1 ATP each to transport (- 2 ATP) • Each FADH2 drives synthesis of 2 ATP • 2 FADH2 ‘s from Citric acid cycle • 4 ATP • Net gain from ETC = 32 ATP

  19. Overview of Oxidative Metabolism • Glycolysis • 2ATP (net gain), 2 NADH • anaerobic, in cytoplasm • Oxidation of Pyruvate • 2 NADH • Citric Acid Cycle • 2ATP, 6 NADH, 2 FADH2 • aerobic, in mitochondria • ETC • 32 ATP (net gain), H2O • in christae of mitochondria

  20. Fermentation Anaerobic Respiration: allowing Glycolysis to continue without O2

  21. Alcoholic Fermentation • Pyruvate from glycolysis is oxidized • forms acetyl • CO2 also formed • Acetyl combines with H from NADH (from gly) • forms ethyl alcohol • also forms NAD to be used in glycolysis • Alcohol becomes toxic @ 12 % • ceases fermentation • thats why fermented drinks have max alcohol of 12% • Uses: wine, brewing, baking

  22. Lactic Acid Fermentation • Pyruvate from glycolysis doesnt get oxidized • an enzyme helps to bond H from NADH to pyruvate • forms Lactic Acid - “Ooooh feel the burn!” • makes NAD available for glycolysis to continue • Occurs in aerobic cells under O2 stress - muscle • Also occurs in certain other microorganisms • sour cream, yogurt • vinegar

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