AP Bio Ch 8 PowerPoint

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Harvesting Energy: Glycolysis and Cellular Respiration

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AP Bio Ch 8 PowerPoint

  1. 1. Chapter 8 Harvesting Energy
  2. 2. Chapter 8 2 Overview of Glucose Breakdown The overall equation for the complete breakdown of glucose is: C6H12O6 + 6O2  6CO2 + 6H2O + ATP The main stages of glucose metabolism are: • Glycolysis • Cellular respiration
  3. 3. Chapter 8 3
  4. 4. Chapter 8 4 Overview of Glucose Breakdown Glycolysis • Occurs in the cytosol • Does not require oxygen • Breaks glucose into pyruvate • Yields two molecules of ATP per molecule of glucose
  5. 5. Chapter 8 5 Overview of Glucose Breakdown If oxygen is absent fermentation occurs • pyruvate is converted into either lactate, or into ethanol and CO2 If oxygen is present cellular respiration occurs…
  6. 6. Chapter 8 6 Overview of Glucose Breakdown Cellular respiration • Occurs in mitochondria (in eukaryotes) • Requires oxygen • Breaks down pyruvate into carbon dioxide and water • Produces an additional 32 or 34 ATP molecules, depending on the cell type
  7. 7. Chapter 8 7 Glycolysis Overview of the two major phases of glycolysis • Glucose activation phase • Energy harvesting phase
  8. 8. Chapter 8 8 Glycolysis Glucose activation phase • Glucose molecule converted to highly reactive fructose bisphosphate by two enzyme-catalyzed reactions, using 2 ATPs
  9. 9. Chapter 8 9 Essentials of Glycolysis (a) Glucose-6- ATP ADP P Phosphate Glucose CCCCCC CCCCCC Glucose-6- Fructose-1,6- P P Phosphate Bisphosphate CCCCCC CCCCCC P ATP ADP
  10. 10. Chapter 8 10 Glycolysis Energy harvesting phase • Fructose bisphosphate is split into two three-carbon molecules of glyceraldehyde 3-phosphate (G3P) • In a series of reactions, each G3P molecule is converted into a pyruvate, generating two ATPs per conversion, for a total of four ATPs • Because two ATPs were used to activate the glucose molecule there is a net gain of two ATPs per glucose molecule
  11. 11. Chapter 8 11 Essentials of Glycolysis (b) Fructose-1,6- P Bisphosphate CCCCCC P P CCC CCC P CCC CCC G3P P P
  12. 12. Chapter 8 12 Glycolysis Energy harvesting phase (continued) • As each G3P is converted to pyruvate, two high-energy electrons and a hydrogen ion are added to an “empty” electron-carrier NAD+ to make the high- energy electron-carrier molecule NADH • Because two G3P molecules are produced per glucose molecule, two NADH carrier molecules are formed
  13. 13. Chapter 8 13 Essentials of Glycolysis (c) CCC CCC G3P Pi Pi P P NAD+ NAD+ NADH NADH CCC CCC P P P P ADP ADP ADP ADP ATP ATP ATP ATP C C C Pyruvates C C C
  14. 14. Chapter 8 14 Glycolysis Summary of glycolysis: • Each molecule of glucose is broken down to two molecules of pyruvate • A net of two ATP molecules and two NADH (high-energy electron carriers) are formed
  15. 15. Chapter 8 15 Fermentation of Dough
  16. 16. Chapter 8 16 Fermentation Pyruvate is processed differently under aerobic and anaerobic conditions Under aerobic conditions, the high energy electrons in NADH produced in glycolysis are ferried to ATP- generating reactions in the mitochondria, making NAD+ available to recycle in glycolysis
  17. 17. Chapter 8 17 Fermentation Under anaerobic conditions, pyruvate is converted into lactate or ethanol, a process called fermentation Fermentation does not produce more ATP, but is necessary to regenerate the high-energy electron carrier molecule NAD+, which must be available for glycolysis to continue
  18. 18. Chapter 8 18 Fermentation Some microbes ferment pyruvate to other acids (as seen in making of cheese, yogurt, sour cream) Some microbes perform fermentation exclusively (instead of aerobic respiration) Yeast cells perform alcoholic fermentation
  19. 19. Chapter 8 19 Alcoholic Fermentation O C O O C O NAD NAD NADH NADH + + NAD+ NAD+ NADH NADH CCC CC Alcoholic Glycolysis CCCCCC Fermentation C C Glucoses CCC Pyruvates Ethanols ADP ATP ADP ATP
  20. 20. Chapter 8 20 Fermentation Some cells ferment pyruvate to form acids Human muscle cells can perform fermentation • Anaerobic conditions produced when muscles use up O2 faster than it can be delivered (e.g. while sprinting) • Lactate (lactic acid) produced from pyruvate
  21. 21. Chapter 8 21 Lactate Fermentation NAD+ NADH NADH NAD+ NAD+ NADH NADH NAD+ CCC CCC Lactate Glycolysis CCCCCC Fermentation C C C Glucoses CCC Pyruvates Lactates ADP ATP ADP ATP
  22. 22. Chapter 8 22 Cellular Respiration In eukaryotic cells, cellular respiration occurs within mitochondria, organelles with two membranes that produce two compartments • The inner membrane encloses a central compartment containing the fluid matrix • The outer membrane surrounds the organelle, producing an intermembrane space
  23. 23. Chapter 8 23 A Mitochondrion One of Its Mitochondria a b A Cell A Crista Outer & Inner Membranes c Intermembrane Matrix Compartment
  24. 24. Chapter 8 24 Cellular Respiration Overview of Aerobic Cellular Respiration: Glucose is first broken down into pyruvate, through glycolysis, in the cell cytoplasm Pyruvate is transported into the mitochondrion (eukaryotes) and split into CO2 and a 2 carbon acetyl group
  25. 25. Chapter 8 25 Cellular Respiration The acetyl group is further broken down into CO2 in the Krebs Cycle (matrix space) as electron carriers are loaded Electron carriers loaded up in glycolysis and the Krebs Cycle give up electrons to the electron transport chain (ETC) along the inner mitochondrial membrane
  26. 26. Chapter 8 26 Cellular Respiration A hydrogen ion gradient produced by the ETC is used to make ATP (chemiosmosis) ATP is transported out of the mitochondrion to provide energy for cellular activities
  27. 27. Chapter 8 27 Cellular Respiration
  28. 28. Chapter 8 28 Pyruvate Breakdown in Mitochondria After glycolysis, pyruvate diffuses into the mitochondrion into the matrix space Pyruvate is split into CO2 and a 2-carbon acetyl group, generating 1 NADH per pyruvate
  29. 29. Chapter 8 29 Pyruvate Breakdown in Mitochondria Acetyl group is carried by a helper molecule called Coenzyme A, now called Acetyl CoA Acetyl CoA enters the Krebs Cycle and is broken down into CO2
  30. 30. Chapter 8 30 Pyruvate Breakdown in Mitochondria Electron carriers NAD+ and FAD are loaded with electrons to produce 3 NADH & 1 FADH2 per Acetyl CoA 6. One ATP also made per Acetyl CoA in the Krebs Cycle
  31. 31. Chapter 8 31 Formation of Acetyl CoA O O C C CCC Pyruvates C C C O O NAD+ NAD+ NADH NADH CCC CCC CoA CoA CoA CoA C C Acetyl CoA C C
  32. 32. Chapter 8 32 Krebs Cycle: Summary CoA CoA CoA CoA C C Acetyl CoA C C 1 C C CCCCC CCCCC O O CCCC CCCC C C NAD NAD + + O O NADH NADH 2 3 NADH NADH C CCCCC CCCCC NAD+ NAD+ H2O H2O 567 NAD+ NAD+ FADH2 O O FADH2 NADH NADH C C FAD O O FAD ADP ADP ATP ATP 4 CCCC CCCCC H 2O H 2O
  33. 33. Chapter 8 33 Electron Transport Chain Most of the energy in glucose is stored in electron carriers NADH and FADH2 • Only 4 total ATP produced per glucose after complete breakdown in the Krebs Cycle
  34. 34. Chapter 8 34 Electron Transport Chain NADH and FADH2 deposit electrons into electron transport chains in the inner mitochondrial membrane Electrons join with oxygen gas and hydrogen ions to made H2O at the end of the ETCs
  35. 35. Chapter 8 35 Mitochondrial Electron Transport System
  36. 36. Chapter 8 36 Chemiosmosis Energy is released from electrons as they are passed down the electron transport chain Released energy used to pump hydrogen ions across the inner membrane • Hydrogen ions accumulate in intermembrane space
  37. 37. Chapter 8 37 Chemiosmosis Hydrogen ions form a concentration gradient across the membrane, a form of stored energy Hydrogen ions flow back into the matrix through an ATP synthesizing enzyme • Process is called chemiosmosis
  38. 38. Chapter 8 38 Chemiosmosis Flow of hydrogen ions provides energy to link 32-34 molecules of ADP with phosphate, forming 32-34 ATP ATP then diffuses out of mitochondrion and used for energy-requiring activities in the cell
  39. 39. Chapter 8 39 Mitochondrial Chemiosmosis (1)
  40. 40. Chapter 8 40 Mitochondrial Chemiosmosis (2)
  41. 41. Chapter 8 41 Mitochondrial Chemiosmosis (3)
  42. 42. Chapter 8 42 Influence on How Organisms Function Metabolic processes in cells are heavily dependent on ATP generation (cyanide kills by preventing this) Muscle cells switch between fermentation and aerobic cell respiration depending on O2 availability
  43. 43. Chapter 8 43 Energy Harvested from Glucose
  44. 44. Chapter 8 44 Energy Harvested from Glucose Glucose (Cytoplasm) 4 ATP Glycolysis 2 ATP 2 Pyruvates 2 NADH (Mitochondrial 2 CO2 2 NADH Matrix) Krebs 4 CO2 6 NADH Cycle 2 FADH2 2 ATP (Inner Membrane) Water Electron Transport System Oxygen 32 ATP
  45. 45. Chapter 8 The end

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