Tang 02 cellular respiration

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  • http://www.youtube.com/watch?v=j7gPtASv0SQ (good summary video)
  • Recap what was in the TVO video. - two conditions under which glucose can be metabolised
  • Think entropy!!!
  • Recall from video
  • Tang 02 cellular respiration

    1. 1. Cellular Respiration In the presence of oxygen: aerobic cellular respiration In the absence of oxygen: alcoholic fermentation (yeast) lactic acid fermentation (humans)
    2. 2. Goals of Cellular Respiration 1. To break 6-carbon glucose down and release 6 molecules of CO2 2. Move glucose electrons to O2, and combine with H+ ions to form 6 molecules of H2O 3. Collect energy in the form of ATP
    3. 3. Four Major Stages 1. Glycolysis 2. Oxidative decarboxylation (pyruvate oxidation) 3. Krebs cycle 4. Electron Transport Chain (oxidative phosphorylation / OXPHOS) cytoplasm mitochondrial matrix mitochondrial matrix inner mitochondrial membrane
    4. 4. Four Major Stages
    5. 5. Glycolysis
    6. 6. Glycolysis glycolysis – breaking down glucose molecules Specifically, glucose (6 carbon molecule) is broken down into the final product of two pyruvate molecules (3 carbon molecule)
    7. 7. Glycolysis
    8. 8. Glycolysis: What to know! 1. What is the purpose of each step? 2. What type of reaction is happening? 3. What type of enzyme is used? (NOT THE ENZYME NAME!) 4. Energy distribution at each step.
    9. 9. Glycolysis: Two major phases 1. investment phase – energy (ATP) used up to split the molecule  steps 1 through 5 1. pay-off phase – energy molecules (ATP and NADH) are produced  steps 6 through 10
    10. 10. Glycolysis: Step by Step Step 1: Carbon 6 phosphorylated using ATP to prevent glucose from leaving the cell rxn type: phosphorylation enzyme: kinase energy: absorbed
    11. 11. Glycolysis: Step by Step Step 2: Atoms of molecule are rearranged rxn type: isomerization enzyme: isomerase energy: equivalent
    12. 12. Glycolysis: Step by Step Step 3: Carbon 1 phosphorylated to produce an energetically unstable product rxn type: phosphorylation enzyme: kinase energy: absorbed
    13. 13. Glycolysis: Step by Step Step 4: The high energy molecule is split into two molecules rxn type: cleavage enzyme: lyase energy: equivalent
    14. 14. Glycolysis: Step by Step Step 5: DHAP and G3P are isomers G3P is used in many other metabolic pathways rxn type: isomerization enzyme: isomerase energy: equivalent Only glyceraldehyde-3- phosphate will continue to be used in glycolysis.
    15. 15. Glycolysis: Step by Step Step 6: NADH (energy molecule) is created rxn type: redox phosphorylation enzyme: dehydrogenase energy: released
    16. 16. NAD+ / NADH NAD+ – nicotinamide adenine dinucleotide (oxidized form) NADH – nicotinamide adenine dinucletide (reduced form)
    17. 17. NAD+ / NADH reduced oxidized
    18. 18. Glycolysis: Step by Step Step 7: ADP phosphorylation to create ATP rxn type: substrate-level phosphorylation enzyme: kinase energy: released
    19. 19. Glycolysis: Step by Step Step 8: Phosphate moved from carbon 3 to carbon 2 rxn type: isomerization enzyme: isomerase energy: equivalent
    20. 20. Glycolysis: Step by Step Step 9: Water removed to set up next reaction rxn type: dehydration enzyme: lyase energy: released
    21. 21. Glycolysis: Step by Step Step 10: ADP phosphorylation to ATP rxn type: substrate-level phosphorylation enzyme: kinase energy: released
    22. 22. Two Methods of ATP formation 1. substrate-level phosphorylation 2. oxidative phosphorylation (OXPHOS) direct ATP formation through phosphate transfer from a molecule to ADP indirect ATP formation through redox reactions involving O2 as a final electron acceptor glycolysis & Kreb cycle electron transport chain
    23. 23. Glycolysis Summary 1. glucose  2 pyruvate 2. net 2 ATP molecules produced  2 used; 4 generated 1. 2 NADH molecules produced
    24. 24. Gluconeogenesis gluconeogensis – generation of glucose from pyruvate
    25. 25. Glycolysis summary
    26. 26. Aerobic Metabolism NADH and pyruvate will continue through Kreb cycle and the ETC to synthesize ATP only in the presence of O2. In the absence of O2, cells still want to try to make as much energy as possible using only glycolysis.
    27. 27. Anaerobic Metabolism Two types: 1.lactic acid fermentation (humans) 2.alcohol fermentation (yeast)
    28. 28. 1. Lactic Acid Fermentation
    29. 29. 1. Lactic Acid Fermentation In the absence of O2, lactate dehydrogenase converts pyruvate into lactic acid in humans. lactic acid (lactate) is a 3 carbon molecule NADH is converted back into NAD+ for glycolysis to continue to occur. Once enough O2 has returned to the cells, lactic acid is converted back into pyruvate.
    30. 30. 2. Alcohol Fermentation In the absence of O2: 1.pyruvate is decarboxylated (loss of CO2) into acetaldehyde 2.alcohol dehydrogenase converts acetaldehyde into ethanol NADH is converted back into NAD+ for glycolysis to continue to occur. Ethanol will not be converted back to pyruvate even if O2 concentration has increased due to loss of CO2.
    31. 31. 2. Alcohol Fermentation
    32. 32. Anaerobic Fermentation Summary 1. lactic acid fermentation 1. pyruvate  lactic acid 2. NADH  NAD+ 2. alcohol fermentation 1. pyruvate  acetaldehyde  ethanol 2. CO2 released 3. NADH  NAD+

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