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QUESTION OF THE DAY… All E. coli look alike through a microscope; so how can E. coli O157 be differentiated? Copyright © 2010 Pearson Education, Inc. Catabolic and Anabolic Reactions Metabolism: The sum of the chemical reactions in an organism __________: Provides energy and building blocks for anabolism. __________: Uses energy and building blocks to build large molecules Copyright © 2010 Pearson Education, Inc. Role of ATP in Coupling Reactions QUESTION: How is ATP an intermediate between catabolism and anabolism? Figure 5.1 Copyright © 2010 Pearson Education, Inc. Catabolic and Anabolic Reactions 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 Copyright © 2010 Pearson Education, Inc. Collision Theory 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 © 2010 Pearson Education, Inc. Energy Requirements of a Chemical Reaction Copyright © 2010 Pearson Education, Inc. Figure 5.2 Enzyme Components Biological catalysts Specific for a chemical reaction; not used up in that reaction Apoenzyme: Protein Cofactor: Nonprotein component Coenzyme: Organic cofactor Important Coenzymes: NAD+, NADP+, FAD, Coenzyme A Holoenzyme: Apoenzyme plus cofactor Copyright © 2010 Pearson Education, Inc. Components of a Holoenzyme Copyright © 2010 Pearson Education, Inc. Figure 5.3 Enzyme Specificity and Efficiency The turnover number is generally 1 to 10,000 molecules per second Copyright © 2010 Pearson Education, Inc. The Mechanism of Enzymatic Action Copyright © 2010 Pearson Education, Inc. Figure 5.4b 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 © 2010 Pearson Education, Inc. Factors Influencing Enzyme Activity Temperature – Denatures proteins pH – Denatures proteins Substrate concentration – Specificity of enzymes Inhibitors – Prevent binding of substate/enzyme Copyright © 2010 Pearson Education, Inc. Effect of Temperature on Enzyme Activity QUESTION: What happens to an enzyme below its optimal temperature? Copyright © 2010 Pearson Education, Inc. Figure 5.5a Effect of pH on Enzyme Activity Copyright © 2010 Pearson Education, Inc. Figure 5.5b Effect of Substrate Concentration on Enzyme Activity Copyright © 2010 Pearson Education, Inc. Figure 5.5c Enzyme Inhibitors: Competitive Inhibition Copyright © 2010 Pearson Education, Inc. Figure 5.7a–b Enzyme Inhibitors: Competitive Inhibition Copyright © 2010 Pearson Education, Inc. Enzyme Inhibitors: Noncompetitive Inhibition Copyright © 2010 Pearson Education, Inc. Figure 5.7a, c Enzyme Inhibitors: Feedback Inhibition QUESTION: Why is feedback inhibition noncompetitive inhibition? Copyright © 2010 Pearson Education, Inc. Figure 5.8 Ribozymes RNA that cuts and splices RNA Copyright © 2010 Pearson Education, Inc. Oxidation-Reduction Oxidation: Removal of electrons Reduction: Gain of electrons Redox reaction: An oxidation reaction paired with a reduction reaction Copyright © 2010 Pearson Education, Inc. Figure 5.9 Oxidation-Reduction Reactions In biological systems, the electrons are often associated with hydrogen atoms. Biological oxidations are often dehydrogenations. Copyright © 2010 Pearson Education, Inc. The Generation of ATP ATP is generated by the phosphorylation of ADP Copyright © 2010 Pearson Education, Inc. Substrate-Level Phosphorylation Energy from the transfer of a high-energy PO4– to ADP generates ATP Copyright © 2010 Pearson Education, Inc. Oxidative Phosphorylation Energy released from transfer of electrons (oxidation) of one compound to another (reduction) is used to generate ATP in the electron transport chain Copyright © 2010 Pearson Education, Inc. Photophosphorylation Light causes chlorophyll to give up electrons. Energy released from transfer of electrons (oxidation) of chlorophyll through a system of carrier molecules is used to generate ATP. QUESTION: Can you outline the three ways that ATP is generated? Copyright © 2010 Pearson Education, Inc. Metabolic Pathways of Energy Production Copyright © 2010 Pearson Education, Inc. Carbohydrate Catabolism The breakdown of carbohydrates to release energy Glycolysis Krebs cycle Electron transport chain REVIEW THESE CONCEPTS FROM CELL BIOLOGY!! Copyright © 2010 Pearson Education, Inc. 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 QUESTION: What is the value of the pentose phosphate and EntnerDoudoroff pathways if they produce only one ATP molecule? Copyright © 2010 Pearson Education, Inc. Overview of Respiration and Fermentation Copyright © 2010 Pearson Education, Inc. Figure 5.11 Chemiosmotic Generation of ATP QUESTION: How do carrier molecules function in the electron transport chain? Copyright © 2010 Pearson Education, Inc. Figure 5.16 An Overview of Chemiosmosis Copyright © 2010 Pearson Education, Inc. Figure 5.15 A Summary of 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 operates under anaerobic conditions. Copyright © 2010 Pearson Education, Inc. Anaerobic Respiration Electron Acceptor Products NO3– NO2–, N2 + H2O SO4– H2S + H2O CO32 – CH4 + H2O Copyright © 2010 Pearson Education, Inc. Carbohydrate Catabolism Pathway Eukaryote Prokaryote Glycolysis Cytoplasm Cytoplasm Intermediate step Cytoplasm Cytoplasm Krebs cycle Mitochondrial matrix Cytoplasm ETC Mitochondrial inner membrane Plasma membrane Copyright © 2010 Pearson Education, Inc. Carbohydrate Catabolism 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 © 2010 Pearson Education, Inc. Carbohydrate Catabolism ATP produced from complete oxidation of one glucose using aerobic respiration Pathway By Substrate-Level Phosphorylation By Oxidative Phosphorylation From NADH From FADH 0 Glycolysis 2 6 Intermediate step 0 6 Krebs cycle 2 18 4 Total 4 30 4 Copyright © 2010 Pearson Education, Inc. Carbohydrate Catabolism 36 ATPs are produced in eukaryotes Pathway By Substrate-Level Phosphorylation By Oxidative Phosphorylation From NADH From FADH 0 Glycolysis 2 6 Intermediate step 0 6 Krebs cycle 2 18 4 Total 4 30 4 Copyright © 2010 Pearson Education, Inc. Fermentation Any spoilage of food by microorganisms (general use) Any process that produces alcoholic beverages or acidic dairy products (general use) Any large-scale microbial process occurring with or without air (common definition used in industry) Copyright © 2010 Pearson Education, Inc. Fermentation Scientific definition: Releases energy from oxidation of organic molecules Does not require oxygen Does not use the Krebs cycle or ETC Uses an organic molecule as the final electron acceptor Copyright © 2010 Pearson Education, Inc. An Overview of Fermentation ANIMATION Fermentation Copyright © 2010 Pearson Education, Inc. Figure 5.18a End-Products of Fermentation Copyright © 2010 Pearson Education, Inc. Figure 5.18b Fermentation Alcohol fermentation: Produces ethanol + CO2 Lactic acid fermentation: Produces lactic acid Homolactic fermentation: Produces lactic acid only Heterolactic fermentation: Produces lactic acid and other compounds Copyright © 2010 Pearson Education, Inc. Types of Fermentation Compare the energy yield (ATP) of aerobic and anaerobic respiration – which one is more efficient? Copyright © 2010 Pearson Education, Inc. Figure 5.19 A Fermentation Test Copyright © 2010 Pearson Education, Inc. Figure 5.23 Types of Fermentation Copyright © 2010 Pearson Education, Inc. Table 5.4 Lipid Catabolism Copyright © 2010 Pearson Education, Inc. Figure 5.20 Catabolism of Organic Food Molecules Copyright © 2010 Pearson Education, Inc. Figure 5.21 Protein Catabolism Protein Extracellular proteases Deamination, decarboxylation, dehydrogenation, desulfurylation Copyright © 2010 Pearson Education, Inc. Amino acids Organic acid Krebs cycle Protein Catabolism Decarboxylation Copyright © 2010 Pearson Education, Inc. Figure 5.22 Protein Catabolism Desulfurylation Copyright © 2010 Pearson Education, Inc. Figure 5.24 Protein Catabolism Urea Urease Copyright © 2010 Pearson Education, Inc. NH3 + CO2 Clinical Focus Figure B Biochemical Tests Used to identify bacteria. QUESTION: Could biochemical tests be used to differentiate between Pseudomonas and Escherichia – explain. Copyright © 2010 Pearson Education, Inc. Clinical Focus Figure A Photosynthesis Photo: Conversion of light energy into chemical energy (ATP) Light-dependent (light) reactions Synthesis: Carbon fixation: Fixing carbon into organic molecules Light-independent (dark) reaction: Calvin-Benson cycle Copyright © 2010 Pearson Education, Inc. Photosynthesis Oxygenic: 6 CO2 + 12 H2O + Light energy C6H12O6 + 6 H2O + 6 O2 Anoxygenic: 6 CO2 + 12 H2S + Light energy C6H12O6 + 6 H2O + 12 S QUESTION: How is photosynthesis important to catabolism? Copyright © 2010 Pearson Education, Inc. Cyclic Photophosphorylation QUESTION: What is made during the light-dependent reactions? Copyright © 2010 Pearson Education, Inc. Figure 5.25a Noncyclic Photophosphorylation QUESTION: How are oxidative phosphorylation and photophosphorylation similar? Copyright © 2010 Pearson Education, Inc. Figure 5.25b Calvin-Benson Cycle Copyright © 2010 Pearson Education, Inc. Figure 5.26 Photosynthesis Compared Copyright © 2010 Pearson Education, Inc. Table 5.6 Requirements of ATP Production Phototrophs verses Chemotrophs Copyright © 2010 Pearson Education, Inc. Figure 5.27 A Nutritional Classification of Organisms Copyright © 2010 Pearson Education, Inc. Figure 5.28 A Nutritional Classification of Organisms Copyright © 2010 Pearson Education, Inc. Figure 5.28 A Nutritional Classification of Organisms Copyright © 2010 Pearson Education, Inc. Figure 5.28 Metabolic Diversity among Organisms Nutritional Type Energy Source Carbon Source Example Photoautotroph Light CO2 Oxygenic: Cyanobacteria plants Anoxygenic: Green, purple bacteria Photoheterotroph Light Organic compounds Green, purple nonsulfur bacteria Chemoautotroph Chemical CO2 Iron-oxidizing bacteria Chemoheterotroph Chemical Organic compounds Fermentative bacteria Animals, protozoa, fungi, bacteria. QUESTION: Almost all medically important microbes belong to which of the four aforementioned groups? Copyright © 2010 Pearson Education, Inc. Polysaccharide Biosynthesis Copyright © 2010 Pearson Education, Inc. Figure 5.29 Lipid Biosynthesis Copyright © 2010 Pearson Education, Inc. Figure 5.30 Pathways of Amino Acid Biosynthesis Copyright © 2010 Pearson Education, Inc. Figure 5.31a Amino Acid Biosynthesis Copyright © 2010 Pearson Education, Inc. Figure 5.31b Purine and Pyrimidine Biosynthesis Copyright © 2010 Pearson Education, Inc. Figure 5.32 The Integration of Metabolism Amphibolic pathways: Metabolic pathways that have both catabolic and anabolic functions Glycolysis Copyright © 2010 Pearson Education, Inc. Kreb’s Cycle