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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings PowerPoint ® Lecture Slide Presentation prepared by Christine L. Case M I C R O B I O L O G Y a n i n t r o d u c t i o n ninth edition TORTORA FUNKE CASE Part A 5 Microbial Metabolism
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Metabolism: The sum of the chemical reactions in an organism Catabolism: The energy-releasing processes Anabolism: The energy-using processes Microbial Metabolism
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Microbial Metabolism Catabolism provides the building blocks and energy for anabolism. Figure 5.1
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings A metabolic pathway is a sequence of enzymatically catalyzed chemical reactions in a cell. Metabolic pathways are determined by enzymes. Enzymes are encoded by genes. PLAY Animation: Metabolic Pathways (Overview)
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Activation energy is needed to disrupt electronic configurations. Reaction rate is the frequency of collisions with enough energy to bring about a reaction. Reaction rate can be increased by enzymes or by increasing temperature or pressure.
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Enzymes Figure 5.2
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Enzymes Biological catalysts Specific for a chemical reaction; not used up in that reaction Apoenzyme: Protein Cofactor: Nonprotein component Coenzyme: Organic cofactor Holoenzyme: Apoenzyme plus cofactor
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Enzymes Figure 5.3
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Important Coenzymes NAD + NADP + FAD Coenzyme A
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Enzymes The turnover number is generally 1-10,000 molecules per second. PLAY Animation: Enzyme–Substrate Interactions Figure 5.4
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.4 - Overview
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Factors Influencing Enzyme Activity Enzymes can be denatured by temperature and pH Figure 5.6
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Factors Influencing Enzyme Activity Temperature Figure 5.5a
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Factors Influencing Enzyme Activity pH Figure 5.5b
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Factors Influencing Enzyme Activity Substrate concentration Figure 5.5c Saturation
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Factors Influencing Enzyme Activity Competitive inhibition Figure 5.7a–b Examples: Poisons such as cyanide, arsenic, and mercury.
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Factors Influencing Enzyme Activity
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Factors Influencing Enzyme Activity Noncompetitive inhibition Figure 5.7a, c Example: Fluoride
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Factors Influencing Enzyme Activity Feedback inhibition Figure 5.8
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Oxidation-Reduction Oxidation is the removal of electrons. Reduction is the gain of electrons. Redox reaction is an oxidation reaction paired with a reduction reaction. Figure 5.9
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.10
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings The Generation of ATP ATP is generated by the phosphorylation of ADP.
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings The Generation of ATP Substrate-level phosphorylation is the transfer of a high-energy PO 4 3– (PO 4 H 2 – ) to ADP.
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings The Generation of ATP Oxidative Phosphorylation: Energy released from the transfer of electrons (oxidation) of one compound to another (reduction) is used to generate ATP by chemiosmosis.
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Chemiosmosis
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings The Generation of ATP Photophosphorylation: Light causes chlorophyll to give up electrons. Energy released from the transfer of electrons (oxidation) of chlorophyll through a system of carrier molecules is used to generate ATP.
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Photophosphorylation
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Metabolic Pathways
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Carbohydrate Catabolism The breakdown of carbohydrates to release energy Glycolysis Krebs cycle Electron transport chain
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Glycolysis The oxidation of glucose to pyruvic acid produces ATP and NADH. Figure 5.11, step 1
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Glycolysis Glucose + 2 ATP + 4 ADP + 2 PO 4 – + 2 NAD + 2 pyruvic acid + 4 ATP + 2 NADH + 2H + PLAY Animation: Glycolysis
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cellular Respiration Oxidation of molecules liberates electrons for an electron transport chain. ATP is generated by oxidative phosphorylation.
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Krebs Cycle Oxidation of acetyl CoA produces NADH and FADH 2. PLAY Animation: Krebs Cycle
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings The Electron Transport Chain A series of carrier molecules that are, in turn, oxidized and reduced as electrons are passed down the chain. Energy released can be used to produce ATP by chemiosmosis. PLAY Animation: Electron Transport Chains and Chemiosmosis
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Chemiosmosis Figure 5.16
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Chemiosmosis Figure 5.15
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Respiration Aerobic respiration: The final electron acceptor in the electron transport chain is molecular oxygen (O 2 ). Anaerobic respiration: The final electron acceptor in the electron transport chain is not O 2. Yields less energy than aerobic respiration because only part of the Krebs cycles operations under anaerobic conditions.
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Electron acceptorProducts NO 3 – NO 2 –, N 2 + H 2 O SO 4 – H 2 S + H 2 O CO 3 2 – CH 4 + H 2 O Anaerobic Respiration
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings PathwayEukaryoteProkaryote GlycolysisCytoplasm Krebs cycleMitochondrial matrixCytoplasm ETC Mitochondrial inner membrane Plasma membrane Location Comparison
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Pathway By substrate- level phosphorylation By oxidative phosphorylation From NADH From FADH Glycolysis260 Intermediate step06 Krebs cycle2184 Total4304 ATP produced from complete oxidation of one glucose using aerobic respiration. 36 ATPs are produced in eukaryotes.
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