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Microbial Metabolism:  The Chemical Crossroads  of Life Chapter 8 Copyright  ©  The McGraw-Hill Companies, Inc) Permission...
Metabolism <ul><li>Catabolism </li></ul><ul><li>Anabolism </li></ul><ul><li>Energy </li></ul><ul><ul><li>ATP </li></ul></u...
Enzymes <ul><li>Biological catalysts  critical for life </li></ul><ul><li>Nearly always  proteins </li></ul><ul><li>Active...
Reaction Energetics <ul><li>Activation energy </li></ul><ul><li>Lowered by enzyme </li></ul><ul><li>Exergonic  releases en...
Enzyme Pathways <ul><li>Linking products to substrates </li></ul><ul><li>Sequential modifications </li></ul><ul><li>Result...
Strategy of Metabolism <ul><li>Use catabolism to </li></ul><ul><ul><li>Release energy Capture electrons </li></ul></ul><ul...
Key Intermediates (building blocks) <ul><li>Glucose 6-Phosphate 6-Carbon Glycolysis </li></ul><ul><li>Fructose 6-Phosphate...
Concept Check <ul><li>What type of chemical reaction is illustrated here? </li></ul><ul><ul><li>Exergonic </li></ul></ul><...
ATP <ul><li>Adenosine triphosphate </li></ul><ul><li>Components </li></ul><ul><ul><li>Base (adenine) </li></ul></ul><ul><u...
Substrate Level Phosphorylation <ul><li>ATP can be used to drive reactions </li></ul><ul><ul><li>Glucose +  ATP    Glucos...
Oxidation/Reduction <ul><li>Oxidation  is losing electrons </li></ul><ul><li>Reduction  is gaining electrons </li></ul><ul...
NAD <ul><li>Nicotinamide adenine dinucleotide </li></ul><ul><li>Electron acceptor </li></ul><ul><li>Limited amount in the ...
Glycolysis (Stage 1) Energy is spent in the front end to get more later. Copyright  ©  The McGraw-Hill Companies, Inc. Per...
Glycolysis (Stage 2) Splitting into two molecules doubles the reactants. Copyright  ©  The McGraw-Hill Companies, Inc. Per...
Glycolysis (Stage 3) Break-even point using substrate-level phosphorylation. Copyright  ©  The McGraw-Hill Companies, Inc....
Glycolysis (Stage 4) The payoff - a net yield of ATP by substrate level phosphorylation Copyright  ©  The McGraw-Hill Comp...
Concept Check <ul><li>How many  net  ATP are formed in glycolysis? </li></ul><ul><ul><li>One </li></ul></ul><ul><ul><li>Tw...
Glycolysis Summary <ul><li>One glucose is used </li></ul><ul><li>Partial oxidation of the sugar </li></ul><ul><ul><li>Two ...
The Kreb’s Cycle <ul><li>Complete oxidation to CO 2 </li></ul>C C H 2 H C HO C H 2 CO 2 C C H + C OO – C H 2 C H 2 C O C O...
Kreb’s Cycle Summary <ul><li>Pyruvate 1 </li></ul><ul><ul><li>3 CO 2 </li></ul></ul><ul><ul><li>4 NADH </li></ul></ul><ul>...
Regenerating NAD + <ul><li>From one glucose… </li></ul><ul><li>Glycolysis  = 2 NADH </li></ul><ul><li>Kreb’s cycle  = 8 NA...
Concept Check <ul><li>What is the process of making ATP from the degradation of phosphoenolpyruate called? ADP + Pi + PEP ...
Fermentation <ul><li>Performed by anaerobic microorganisms </li></ul><ul><li>Primary purpose : Regenerate NAD for reuse </...
Fermentation <ul><li>NADH oxidized </li></ul><ul><li>Organic molecule reduced </li></ul><ul><li>Many possible end products...
Redox Potential Energy <ul><li>Molecules differ in their affinity for electrons </li></ul><ul><li>Moving from a good donor...
Electron Transport System <ul><li>NADH oxidized </li></ul><ul><li>Electrons pass through membrane carriers </li></ul><ul><...
Anaerobic Respiration <ul><li>The electron acceptor is  not oxygen </li></ul><ul><ul><li>Examples:  nitrate ,  nitrite , a...
Concept Check <ul><li>Which of these is the best electron acceptor? </li></ul><ul><ul><li>Oxygen </li></ul></ul><ul><ul><l...
Aerobic Respiration <ul><li>The electron acceptor is an  oxygen </li></ul><ul><li>This is a very good acceptor </li></ul><...
Chemiosmosis <ul><li>Proton gradient is potential energy </li></ul><ul><li>Allowing protons back into the cell can be coup...
Aerobic Respiration Yield <ul><li>1 Glucose    6 CO 2 </li></ul><ul><li>2 ATP from glycolysis </li></ul><ul><li>2 NADH fr...
Amphibolism CO 2 H 2 O Glycolysis Anabolism Catabolism Simple products Metabolic pathways Building block Macromolecule Cel...
Oxygenic Photosynthesis <ul><li>Chlorophyll  pigments </li></ul><ul><li>Thylakoid  membrane </li></ul><ul><li>Capture  lig...
Anoxygenic Photosynthesis <ul><li>Purple bacteria  (similar to photosystem II) </li></ul><ul><ul><li>Make ATP </li></ul></...
Calvin Benson Cycle <ul><li>Fix carbon dioxide </li></ul><ul><li>Autotrophs </li></ul><ul><li>Reverse of glycolysis </li><...
Concept Check <ul><li>Where does aerobic respiration occur in a yeast? </li></ul><ul><ul><li>Nucleus </li></ul></ul><ul><u...
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Chapt08 lecture

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Chapt08 lecture

  1. 1. Microbial Metabolism: The Chemical Crossroads of Life Chapter 8 Copyright © The McGraw-Hill Companies, Inc) Permission required for reproduction or display.
  2. 2. Metabolism <ul><li>Catabolism </li></ul><ul><li>Anabolism </li></ul><ul><li>Energy </li></ul><ul><ul><li>ATP </li></ul></ul><ul><ul><li>Gradients </li></ul></ul>Glucose CATABOLISM ANABOLISM ANABOLISM ANABOLISM Relative complexity of molecules + Bacterial cell Macromolecules Nutrients from outside or from internal pathways Pyruvate Acetyl CoA Glyceraldehyde-3-P Amino acids Sugars Nucleotides Fatty acids Proteins Peptidoglycan RNA + DNA Complex lipids Glycolysis Krebs cycle Respiratory chain Fermentation Yields energy Building blocks Precursor molecules ATP NADH Uses energy Uses energy Uses energy; some assembly reactions occur spontaneously. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  3. 3. Enzymes <ul><li>Biological catalysts critical for life </li></ul><ul><li>Nearly always proteins </li></ul><ul><li>Active site </li></ul><ul><li>Substrate(s) </li></ul><ul><li>Cofactors </li></ul>E Products Substrate (S) Enzyme (E) Does not fit ES complex Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  4. 4. Reaction Energetics <ul><li>Activation energy </li></ul><ul><li>Lowered by enzyme </li></ul><ul><li>Exergonic releases energy – catabolism </li></ul><ul><li>Endergonic uses energy – anabolism </li></ul>Energy State of Reaction Energy of activation in the absence of enzyme Energy of activation in the presence of enzyme Progress of Reaction Final state Products Initial state Reactant Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  5. 5. Enzyme Pathways <ul><li>Linking products to substrates </li></ul><ul><li>Sequential modifications </li></ul><ul><li>Results in energy – catabolism </li></ul><ul><li>Results in biosynthesis - anabolism </li></ul>A B C D E U V W X Z Y O 2 O O 1 M N P Q R M A B C N X Y Z Multienzyme Systems Linear Cyclic Example: Glycolysis Example: Krebs cycle Tinput S product Example: Amino acid synthesis Convergent Branched Divergent Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  6. 6. Strategy of Metabolism <ul><li>Use catabolism to </li></ul><ul><ul><li>Release energy Capture electrons </li></ul></ul><ul><ul><li>Liberate building blocks </li></ul></ul><ul><li>Drive anabolism by </li></ul><ul><ul><li>Spending energy </li></ul></ul><ul><ul><li>Using electrons </li></ul></ul><ul><ul><li>Using building blocks </li></ul></ul>O HO H CH 2 OH 6 H OH H H OH C CO 2 C C C C C 5 4 3 2 1 3 H OH Energy Level Of Chemical Compound O 1 2 The energy in electrons and hydrogens is captured and transferred to ATP. ATP is spent to drive the thousands of cell functions. ATP used to perform cellular work Hydrogen ions with electrons Hydrogen ions with electrons ATP Progress of Energy Extraction over Time These reactions lower the available energy in each successive reaction, but they effectively route that energy into useful cell activities. Low High Hydrogen ions with electrons Glucose 2H + + 2e – O 2 H 2 O O 1 – 2 + End products Final electron acceptor Glucose is oxidized as it passes metabolic pathways, resulting in the removal of hydrogens and their accompanying electrons. During part of these pathways, the glucose carbon skeleton is also dismantled, giving rise to the end product CO 2 . Oxidation of glucose by means of enzyme-catalyzed pathways 4 In aerobic metabolism, the electrons and hydrogen ions generated by the respiratory pathways combine with oxygen to produce another rend product, water. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. ― ― ― ―
  7. 7. Key Intermediates (building blocks) <ul><li>Glucose 6-Phosphate 6-Carbon Glycolysis </li></ul><ul><li>Fructose 6-Phosphate 6-Carbon Glycolysis </li></ul><ul><li>Triose Phosphate 3-Carbon Glycolysis </li></ul><ul><li>3-Phosphoglycerate 3-Carbon Glycolysis </li></ul><ul><li>Phosphoenolpyruvate 3-Carbon Glycolysis </li></ul><ul><li>Pyruvate 3-Carbon Glycolysis </li></ul><ul><li>Acetyl CoA 2-Carbon Krebs cycle </li></ul><ul><li> -Ketoglutyrate 5-Carbon Krebs cycle </li></ul><ul><li>Succinyl CoA 4-Carbon Krebs cycle </li></ul><ul><li>Oxaloacetate 4-Carbon Krebs cycle </li></ul><ul><li>Ribose 5-Phosphate 5-Carbon Pentose phosphate </li></ul><ul><li>Erythrose 4-Phosphate 4-Carbon Pentose phosphate </li></ul>
  8. 8. Concept Check <ul><li>What type of chemical reaction is illustrated here? </li></ul><ul><ul><li>Exergonic </li></ul></ul><ul><ul><li>Endergonic </li></ul></ul><ul><ul><li>Spontaneous </li></ul></ul><ul><ul><li>Anabolic </li></ul></ul>Energy State of Reaction Energy of activation in the absence of enzyme Energy of activation in the presence of enzyme Progress of Reaction Final state Products Initial state Reactant Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  9. 9. ATP <ul><li>Adenosine triphosphate </li></ul><ul><li>Components </li></ul><ul><ul><li>Base (adenine) </li></ul></ul><ul><ul><li>Sugar (ribose) </li></ul></ul><ul><ul><li>Phosphate (3) </li></ul></ul><ul><li>Energy stored in the phosphate bonds </li></ul>2H 2e: N NH 2 O H C C C C C C P P N H C C C C C C O P P H H + Oxidizednic otinamide Reducednic otinamide NAD From substrate Adenine Ribose NH 2 NADH + H + Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  10. 10. Substrate Level Phosphorylation <ul><li>ATP can be used to drive reactions </li></ul><ul><ul><li>Glucose + ATP  Glucose-6-phosphate + ADP </li></ul></ul><ul><li>Some compounds can be used to make ATP </li></ul><ul><ul><li>Phosphoenolpyruvate + ADP  pyruvate + ATP </li></ul></ul><ul><li>This is called substrate level phosphorylation </li></ul>
  11. 11. Oxidation/Reduction <ul><li>Oxidation is losing electrons </li></ul><ul><li>Reduction is gaining electrons </li></ul><ul><li>Oxidation is always linked to reduction </li></ul>2 8 1 2 8 2 8 7 2 8 8 1 2 Reduced anion Cl Na Cl Na Reducing agent gives up electrons. Oxidizing agent accepts electrons. Oxidized cation Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  12. 12. NAD <ul><li>Nicotinamide adenine dinucleotide </li></ul><ul><li>Electron acceptor </li></ul><ul><li>Limited amount in the cell </li></ul><ul><li>Must be re-oxidized from the reduced form </li></ul>2H 2e: N NH 2 O H C C C C C C P P N H C C C C C C O P P H H + Oxidizednic otinamide Reducednic otinamide NAD From substrate Adenine Ribose NH 2 NADH + H + Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  13. 13. Glycolysis (Stage 1) Energy is spent in the front end to get more later. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Glucose Glucose 6-Phosphate A A Fructose 6-Phosphate A A Fructose 1,6-Biphosphate
  14. 14. Glycolysis (Stage 2) Splitting into two molecules doubles the reactants. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Fructose 1,6-Biphosphate PGAL & DHAP + 1,3 Bisphospho- glycerate 2X 2 NAD + 2 NADH + 2H + 2
  15. 15. Glycolysis (Stage 3) Break-even point using substrate-level phosphorylation. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1,3 Bisphospho- glycerate 2X 2X 2X A A 2X 3 PGA 2X 2 PGA
  16. 16. Glycolysis (Stage 4) The payoff - a net yield of ATP by substrate level phosphorylation Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 2X Phosphoenolpyruvate 2 PGA 2X 2X A A 2X 2X Pyruvate
  17. 17. Concept Check <ul><li>How many net ATP are formed in glycolysis? </li></ul><ul><ul><li>One </li></ul></ul><ul><ul><li>Two </li></ul></ul><ul><ul><li>Three </li></ul></ul><ul><ul><li>Four </li></ul></ul>
  18. 18. Glycolysis Summary <ul><li>One glucose is used </li></ul><ul><li>Partial oxidation of the sugar </li></ul><ul><ul><li>Two NADH are reduced </li></ul></ul><ul><li>2 ATP are consumed </li></ul><ul><li>4 ATP total are made </li></ul><ul><li>Net of 2 ATP produced </li></ul><ul><li>2 pyruvates are end products </li></ul>
  19. 19. The Kreb’s Cycle <ul><li>Complete oxidation to CO 2 </li></ul>C C H 2 H C HO C H 2 CO 2 C C H + C OO – C H 2 C H 2 C O C OO – C OO – C H 2 H O NAD + CO 2 C H 2 C C C O O S O C S C H 3 C C H 2 C C H 2 Acetyl CoA Isocitric acid 8 8 1 2 3 4 5 5 6 7 7 6 3 2 PO 4 –3 C O C H 3 O C C o A C H 2 C C H H C C C C H C C C C H 2 O C O – O – + H + + H + + H + + C C C H 2 H C CO 2 ATP ADP Succinyl CoA CoA CO 2 NAD H NAD + An additional NADH is formed when malic acid is converted to oxaloacetic acid, which is the final product to enter the cycle again, by reacting with acetyl CoA. Fumaric acid reacts with water to form malic acid. Succinic acid loses 2 Hand 2e – , yielding fumaric acid and generating FADH 2 . Succinyl CoA is converted to succinic acid and regenerates CoA. This releases energy that is captured in ATP. a-ketoglutaric acid loses the second CO 2 and generates another NADH + plus 4C succinyl CoA. Isocitric acid is converted to 5C a-ketoglutaric acid, which yields NADH and CO 2 . Citrate changes the arrangement of atoms to form isocitric acid. The 2 Cacetyl CoA molecule combines with oxaloacetic acid, forming 6C citrate, and releasing CoA. a-ketoglutaric acid NAD H NAD + OO – OO – Citric acid CoA OO – OO – OO – CoA Pyruvic acid From glycolysis NAD H Oxaloacetic acid OO – OO – H 2 O Malic acid OO – HO OO – NAD + NAD H Krebs Cycle OO – OO – FADH 2 FAD OO – OO – Fumaric acid Succinic acid AEROBIC RESPIRATION ANAEROBIC RESPIRATION FERMENTATION Glycolysis Glycolysis Glycolysis Glucose Glucose Glucose ATP NADH ATP NADH ATP NADH 2pyruvate (3C) (6C) 2pyruvate 2pyruvate (6C) (3C) (3C) (6C) CO 2 CO 2 Acety lCoA Acetyl CoA Fermentation FADH 2 NADH ATP Krebs CO 2 Electrons Electron transport ATP produced = 38 O 2 is final electron acceptor. FADH 2 NADH Krebs ATP CO 2 Electrons Electron transport ATP produced = 2 to 36 ATP produced =2 Lactic acid Acetaldehyde Ethanol Or other alcohols, acids, gases An organic molecule is final electron accept or (pyruvate, acetaldehyde etc.). Non oxygen electron acceptors (examples: SO 4 2–, NO 3 –, CO 3 2– ) 1 4 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  20. 20. Kreb’s Cycle Summary <ul><li>Pyruvate 1 </li></ul><ul><ul><li>3 CO 2 </li></ul></ul><ul><ul><li>4 NADH </li></ul></ul><ul><ul><li>1 FADH 2 </li></ul></ul><ul><ul><li>1 ATP </li></ul></ul><ul><li>Pyruvate 2 </li></ul><ul><ul><li>3 CO 2 </li></ul></ul><ul><ul><li>4 NADH </li></ul></ul><ul><ul><li>1 FADH 2 </li></ul></ul><ul><ul><li>1 ATP </li></ul></ul><ul><li>Each glucose has now been completely oxidized to carbon dioxide </li></ul><ul><li>Electrons are temporarily on carrier molecules </li></ul><ul><li>4 ATP total made by substrate level phosphorylation </li></ul>
  21. 21. Regenerating NAD + <ul><li>From one glucose… </li></ul><ul><li>Glycolysis = 2 NADH </li></ul><ul><li>Kreb’s cycle = 8 NADH & 2 FADH 2 </li></ul><ul><li>There is a limited amount of NAD in the cell, so it must be regenerated for reuse later. </li></ul>
  22. 22. Concept Check <ul><li>What is the process of making ATP from the degradation of phosphoenolpyruate called? ADP + Pi + PEP  Pyruvate + ATP </li></ul><ul><ul><li>A. Oxidative phosphorylation </li></ul></ul><ul><ul><li>B. Oxidative decarboxylation </li></ul></ul><ul><ul><li>C. Photophosphorylation </li></ul></ul><ul><ul><li>D. Substrate level phosphorylation </li></ul></ul>
  23. 23. Fermentation <ul><li>Performed by anaerobic microorganisms </li></ul><ul><li>Primary purpose : Regenerate NAD for reuse </li></ul><ul><li>The electron acceptor is an organic molecule </li></ul><ul><li>Secondary purpose : Generate additional energy </li></ul><ul><li>Energy yields are very small </li></ul><ul><li>As a consequence the growth rates are slower </li></ul>
  24. 24. Fermentation <ul><li>NADH oxidized </li></ul><ul><li>Organic molecule reduced </li></ul><ul><li>Many possible end products </li></ul><ul><ul><li>Lactic acid </li></ul></ul><ul><ul><li>Ethanol </li></ul></ul><ul><ul><li>Vinegar </li></ul></ul><ul><ul><li>Acetone </li></ul></ul>C C O O C H H H OH C C H H H H H C C O H H H H C C C H H H H O H O O H System: Homolactic bacteria; human muscle Glucose System: Yeasts Glycolysis Lactic acid Ethyl alcohol Pyruvic acid OH NADH NAD H NADH NAD NAD CO 2 Acetaldehyde O 2 is final electron acceptor. ATP produced = 38 ATP produced = 2 to 36 ATP produced = 2 Non oxygen electron acceptors (examples: SO 4 2–, NO 3 –, CO 3 2– ) An organic molecule is final electron accept or (pyruvate, acetaldehyde, etc.). AEROBIC RESPIRATION Glycolysis Glucose ATP NADH 2pyruvate (3C) (6C) CO 2 Acety lCoA FADH 2 NADH ATP Krebs CO 2 Electrons Electron transport ANAEROBIC RESPIRATION Glycolysis Glucose ATP NADH 2pyruvate (3C) (6C) CO 2 Acety lCoA FADH 2 NADH ATP Krebs CO 2 Electrons Electron transport FERMENTATION CO 2 Glycolysis Glucose ATP NADH 2pyruvate Lactic acid Ethanol Or other alcohols, acids, gases Acetaldehyde (6C) (3C) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  25. 25. Redox Potential Energy <ul><li>Molecules differ in their affinity for electrons </li></ul><ul><li>Moving from a good donor to a good acceptor is favorable and releases energy </li></ul><ul><li>NADH is a good donor </li></ul><ul><li>Oxygen is the best acceptor </li></ul><ul><li>Want to couple this to do work </li></ul>
  26. 26. Electron Transport System <ul><li>NADH oxidized </li></ul><ul><li>Electrons pass through membrane carriers </li></ul><ul><li>Protons pumped out (work is done) </li></ul><ul><li>Electrons accepted by an inorganic molecule </li></ul>H H H H H H H H H H H H H H H H H H H H Cell wall Cytochromes Cytoplasm Cell membrane with ETS ATP ADP ATP synthase Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  27. 27. Anaerobic Respiration <ul><li>The electron acceptor is not oxygen </li></ul><ul><ul><li>Examples: nitrate , nitrite , and sulfate </li></ul></ul><ul><li>These are mediocre acceptors – not as good as oxygen </li></ul><ul><li>Yields other inorganic molecules upon reduction </li></ul><ul><li>Less favorable reactions pump out fewer protons </li></ul>
  28. 28. Concept Check <ul><li>Which of these is the best electron acceptor? </li></ul><ul><ul><li>Oxygen </li></ul></ul><ul><ul><li>Nitrate </li></ul></ul><ul><ul><li>Pyruvate </li></ul></ul><ul><ul><li>NAD </li></ul></ul>
  29. 29. Aerobic Respiration <ul><li>The electron acceptor is an oxygen </li></ul><ul><li>This is a very good acceptor </li></ul><ul><li>Yields water upon reduction </li></ul><ul><li>Because so much energy is released, the cell can pumps out about 10 protons </li></ul><ul><li>Occurs in bacterial membrane and mitochondria of eukaryotes </li></ul>
  30. 30. Chemiosmosis <ul><li>Proton gradient is potential energy </li></ul><ul><li>Allowing protons back into the cell can be coupled to work </li></ul><ul><li>3 protons entering drive the synthesis of 1 ATP </li></ul><ul><li>Oxidative phosphorylation </li></ul>H + F 0 e – H H O O H + 1 / 2 O 2 (c) The distribution of electric potential and the concentration gradient of protons across the membrane drive the synthesis of ATP by ATP synthase. The rotation of this enzyme couples diffusion of H + to the inner compartment with the bonding of ADP and P i . The final event of electron transport is there action of the electrons with the Hand O 2 to form metabolic H 2 O. This step is catalyzed by cytochrome aa 3 . H + H + H + H + H + ATP ADP + P i ATP synthase H + Outer compartment e – Cytochrome aa 3 H + H + H + H + H + H + H + H + H + H + H + H + Inner compartment Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  31. 31. Aerobic Respiration Yield <ul><li>1 Glucose  6 CO 2 </li></ul><ul><li>2 ATP from glycolysis </li></ul><ul><li>2 NADH from glycolysis  6 ATP </li></ul><ul><li>2 ATP from Krebs cycle substrate level </li></ul><ul><li>8 NADH from Krebs cycle  24 ATP </li></ul><ul><li>2 FADH 2 from Krebs cycle  4 ATP </li></ul><ul><li>Total 36-38 ATP per glucose </li></ul>
  32. 32. Amphibolism CO 2 H 2 O Glycolysis Anabolism Catabolism Simple products Metabolic pathways Building block Macromolecule Cell structure Chromosomes Enzymes Membranes Cell wall Storage Membranes Storage Lipids Fats Starch Cellulose Proteins Nucleic acids Nucleotides Amino acids Carbohydrates Fatty acids Beta oxidation Deamination GLUCOSE Pyruvic acid Krebs cycle Acetyl coenzyme A NH 3 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  33. 33. Oxygenic Photosynthesis <ul><li>Chlorophyll pigments </li></ul><ul><li>Thylakoid membrane </li></ul><ul><li>Capture light energy </li></ul><ul><li>Electron transport </li></ul><ul><li>Photophosphorylation </li></ul><ul><li>Makes NADH and ATP </li></ul><ul><li>Oxygen produced </li></ul><ul><li>Algae, plants, and cyanobacteria </li></ul>½ O 2 2e – 2H + P i Photolysis Electron carriers Calvin Cycles A B D C N N N Mg N H + H + H + H + H + H + H + 1 2 3 4 5 6 (a) A cell of the motile alga Chlamydomonas, with a single large chloroplast (magnified cut away view). The chloroplast contains membranous compartments called grana where chlorophyll molecules and the photosystems for the light reactions are located. (b) A chlorophyll molecule, with a central magnesium atom held by a porphyrin ring. Flagellum Nucleus Cell wall Chloroplast Photons Granum Stroma Thylakoid membrane NADPH ATP ADP + NADP 2e – P700 Electron carriers Photosystem I 2e – P680 Photosystem II H 2 O ATP synthase Proton pump Interior of granum (c) The main events of the light reaction shown as an exploded view in one granum. When light activates photosystem II, it sets up a chain reaction, in which electrons are released from chlorophyll. 1 2 3 4 5 6 Both NADPH and ATP are fed into the stroma for the Calvin cycle. The final electron and H + acceptor is NADP, which receives these from photosystem I. Pumping of H + into the interior of the granum produces conditions for ATP to be synthesied. The empty position in photosystem II is replenished photolysis of H 2 O.Other products of photolysis are O 2 and H + These electrons are transported along a chain of carriers to photosystem I. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  34. 34. Anoxygenic Photosynthesis <ul><li>Purple bacteria (similar to photosystem II) </li></ul><ul><ul><li>Make ATP </li></ul></ul><ul><ul><li>Can’t make NADH </li></ul></ul><ul><ul><li>No oxygen produced </li></ul></ul><ul><li>Green bacteria (similar to photosystem I) </li></ul><ul><ul><li>Make ATP </li></ul></ul><ul><ul><li>Also make NADH </li></ul></ul><ul><ul><li>No oxygen produced </li></ul></ul>
  35. 35. Calvin Benson Cycle <ul><li>Fix carbon dioxide </li></ul><ul><li>Autotrophs </li></ul><ul><li>Reverse of glycolysis </li></ul><ul><li>6 CO 2  Glucose </li></ul>P P P P P P P P P P P P P P H H Splitting ADP ATP × 2 ADP ATP Series of 7 Carbon and 5 Carbon intermediates Ribulose-1,5-bisphosphate 5Carbon CO 2 6 Carbon intermediate NADPH × 2 NADP Glyceraldehyde-3 phosphate Glucose Fructose intermediates 1,3-bisphosphoglyceric acid Calvin Cycle 3-phosphoglyceric acid Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  36. 36. Concept Check <ul><li>Where does aerobic respiration occur in a yeast? </li></ul><ul><ul><li>Nucleus </li></ul></ul><ul><ul><li>Cell membrane </li></ul></ul><ul><ul><li>Mitochondria </li></ul></ul><ul><ul><li>Ribosome </li></ul></ul>

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