Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
TORTORA FUNKE CASE ninth edition MICROBIOLOGY an introduction 5 Part A Microbial Metabolism PowerPoint® Lecture Slide Presentation prepared by Christine L. Case Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Microbial Metabolism Metabolism: The sum of the chemical reactions in an organism Catabolism: The energy-releasing processes Anabolism: The energy-using processes Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Microbial Metabolism Catabolism provides the building blocks and energy for anabolism. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.1 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) Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings The collision theory states that chemical reactions can occur when atoms, ions, and molecules collide. 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. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Enzymes Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.2 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 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Enzymes Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.3 Important Coenzymes NAD+ NADP+ FAD Coenzyme A 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 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.4 Enzyme Classification Oxidoreductase: Oxidation-reduction reactions Transferase: Transfer functional groups Hydrolase: Hydrolysis Lyase: Removal of atoms without hydrolysis Isomerase: Rearrangement of atoms Ligase: Joining of molecules, uses ATP Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Factors Influencing Enzyme Activity Enzymes can be denatured by temperature and pH Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.6 Factors Influencing Enzyme Activity Temperature Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.5a Factors Influencing Enzyme Activity pH Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.5b Factors Influencing Enzyme Activity Substrate concentration Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.5c Factors Influencing Enzyme Activity Competitive inhibition Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.7a–b Factors Influencing Enzyme Activity Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Factors Influencing Enzyme Activity Noncompetitive inhibition Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.7a, c Factors Influencing Enzyme Activity Feedback inhibition Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.8 Ribozymes RNA that cuts and splices RNA 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. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.9 Oxidation-Reduction In biological systems, the electrons are often associated with hydrogen atoms. Biological oxidations are often dehydrogenations. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.10 The Generation of ATP ATP is generated by the phosphorylation of ADP. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings The Generation of ATP Substrate-level phosphorylation is the transfer of a high-energy PO4– to ADP. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings The Generation of ATP Energy released from the transfer of electrons (oxidation) of one compound to another (reduction) is used to generate ATP by chemiosmosis. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings The Generation of ATP 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. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Metabolic Pathways Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Carbohydrate Catabolism The breakdown of carbohydrates to release energy Glycolysis Krebs cycle Electron transport chain Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Glycolysis The oxidation of glucose to pyruvic acid produces ATP and NADH. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.11, step 1 Preparatory Stage Two ATPs are used Glucose is split to 1 form two Glucose3-phosphate 3 4 5 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.12, step 1 Energy-Conserving Stage Two Glucose-3- phosphate oxidized to two Pyruvic acid Four ATP produced Two NADH produced 9 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.12, step 2 Glycolysis Glucose + 2 ATP + 2 ADP + 2 PO4– + 2 NAD+ 2 pyruvic acid + 4 ATP + 2 NADH + 2H+ PLAY Animation: Glycolysis Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Alternatives to Glycolysis Pentose phosphate pathway Uses pentoses and NADPH Operates with glycolysis Entner-Doudoroff pathway Produces NADPH and ATP Does not involve glycolysis Pseudomonas, Rhizobium, Agrobacterium 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. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Intermediate Step Pyruvic acid (from glycolysis) is oxidized and decarboyxlated. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.13 (1 of 2) Krebs Cycle Oxidation of acetyl CoA produces NADH and FADH2. PLAY Animation: Krebs Cycle Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Krebs Cycle Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.13 (2 of 2) 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 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.11 Chemiosmosis Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.16 Chemiosmosis Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.15 Respiration Aerobic respiration: The final electron acceptor in the electron transport chain is molecular oxygen (O2). Anaerobic respiration: The final electron acceptor in the electron transport chain is not O2. Yields less energy than aerobic respiration because only part of the Krebs cycles operations under anaerobic conditions. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Anaerobic Respiration Electron acceptor Products NO3– NO2–, N2 + H2O SO4– H2S + H2O CO32 – CH4 + H2O Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Pathway Eukaryote Prokaryote Glycolysis Cytoplasm Cytoplasm Intermediate step Cytoplasm Cytoplasm Krebs cycle Mitochondrial matrix Cytoplasm ETC Mitochondrial inner membrane Plasma membrane Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Energy produced from complete oxidation of one glucose using aerobic respiration. ATP produced NADH produced FADH2 produced Glycolysis 2 2 0 Intermediate step 0 2 Krebs cycle 2 6 2 Total 4 10 2 Pathway Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings ATP produced from complete oxidation of one glucose using aerobic respiration. Pathway By substratelevel phosphorylation By oxidative phosphorylation From From NADH FADH Glycolysis 2 6 Intermediate step 0 6 Krebs cycle 2 18 4 Total 4 30 4 36 ATPs are produced in eukaryotes. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings 0