1 / 45

Harvesting Energy

Harvesting Energy. Overview of Glucose Breakdown. The overall equation for the complete breakdown of glucose is: C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O + ATP The main stages of glucose metabolism are: Glycolysis Cellular respiration. Overview of Glucose Breakdown. Glycolysis

odette
Télécharger la présentation

Harvesting Energy

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 8 Harvesting Energy

  2. Chapter 8 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. Chapter 8

  4. Chapter 8 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. Chapter 8 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. Chapter 8 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. Chapter 8 Glycolysis • Overview of the two major phases of glycolysis • Glucose activation phase • Energy harvesting phase

  8. Chapter 8 Glycolysis • Glucose activation phase • Glucose molecule converted to highly reactive fructose bisphosphate by two enzyme-catalyzed reactions, using 2 ATPs

  9. Chapter 8 Essentials of Glycolysis (a) ATP ADP P P P C C C C C C C C C C C C C C C C C C C C C C C C P ATP ADP Glucose-6-Phosphate Glucose Glucose-6-Phosphate Fructose-1,6-Bisphosphate

  10. Chapter 8 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. Chapter 8 Essentials of Glycolysis (b) Fructose-1,6-Bisphosphate P P P C C C C C C P P C C C C C C C C C C C C P G3P

  12. Chapter 8 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. Chapter 8 Essentials of Glycolysis (c) Pi Pi NAD+ NAD+ NADH NADH P P ADP ADP ADP ADP C C C C C C C C C C C C C C C C C C P P ATP ATP P P ATP ATP G3P Pyruvates

  14. Chapter 8 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. Chapter 8 Fermentation of Dough

  16. Chapter 8 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. Chapter 8 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. Chapter 8 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. Chapter 8 Alcoholic Fermentation O O NADH C C O O NADH C C C C C C C C C C C C C C C C NAD+ NAD+ NADH NAD+ NAD+ NADH AlcoholicFermentation Glycolysis Glucoses Pyruvates Ethanols ADP ATP ADP ATP

  20. Chapter 8 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. Chapter 8 Lactate Fermentation NADH NADH C C C C C C C C C C C C C C C C C C NAD+ NADH NAD+ NAD+ NADH NAD+ LactateFermentation Glycolysis Glucoses Pyruvates Lactates ADP ATP ADP ATP

  22. Chapter 8 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. Chapter 8 A Mitochondrion One of ItsMitochondria a b A Cell A Crista Outer& InnerMembranes c Matrix IntermembraneCompartment

  24. Chapter 8 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. Chapter 8 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. Chapter 8 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. Chapter 8 Cellular Respiration

  28. Chapter 8 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. Chapter 8 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. Chapter 8 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. Chapter 8 Formation of Acetyl CoA O C O O C NAD+ NAD+ O C C C C C C C C CoA CoA NADH NADH CoA CoA C C C C C C C C C C C C Pyruvates Acetyl CoA

  32. Chapter 8 Krebs Cycle: Summary CoA O O O O C C C C O O O O C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C NAD+ NADH NADH NAD+ H2O CoA CoA NAD+ C C C C C C C C FADH2 NADH FAD ADP ATP H2O CoA Acetyl CoA 1 NAD+ NADH 2 3 NADH NAD+ H2O 5 6 7 NAD+ FADH2 NADH FAD ADP ATP 4 H2O

  33. Chapter 8 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. Chapter 8 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. Chapter 8 MitochondrialElectron Transport System

  36. Chapter 8 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. Chapter 8 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. Chapter 8 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. Chapter 8 MitochondrialChemiosmosis (1)

  40. Chapter 8 MitochondrialChemiosmosis (2)

  41. Chapter 8 MitochondrialChemiosmosis (3)

  42. Chapter 8 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. Chapter 8 Energy Harvested from Glucose

  44. Chapter 8 Energy Harvested from Glucose Glucose (Cytoplasm) 4 ATP Glycolysis 2 ATP 2 Pyruvates 2 NADH (MitochondrialMatrix) 2 CO2 2 NADH KrebsCycle 6 NADH 4 CO2 2 FADH2 2 ATP (InnerMembrane) Water Electron TransportSystem 32 ATP Oxygen

  45. Chapter 8 The end

More Related