Slide 1Why is the study of metabolism important?MetabolismMetabolic Processes Guided by Eight Elementary StatementsCatabolism and AnabolismOxidation and Reduction ReactionsOxidation and Reduction ReactionsATP Production and Energy StorageATP Production and Energy StorageThe Roles of Enzymes in MetabolismCarbohydrate CatabolismCarbohydrate CatabolismSteps in Cellular RespirationSteps in Cellular Respiration – Entry MechanismsSteps in Cellular Respiration – Entry MechanismsSteps in Cellular Respiration - CatabolismSteps in Cellular Respiration - CatabolismSteps in Cellular Respiration - CatabolismSteps in Cellular Respiration - CatabolismSteps in Cellular Respiration - CatabolismSteps in Cellular Respiration - CatabolismSteps in Cellular Respiration - CatabolismSteps in Cellular Respiration - CatabolismSteps in Cellular Respiration - BiosynthesisSteps in Cellular Respiration - PolymerizationSteps in Cellular Respiration - AssemblySteps in FermentationSteps in FermentationCarbohydrate CatabolismCarbohydrate CatabolismM I C R O B I O L O G YWITH DISEASES BY BODY SYSTEM SECOND EDITIONChapter 5Microbial MetabolismTHIRDWhy is the study of metabolism important?•As a part of the disease process, pathogens acquire energy and nutrients from a host (and to the detriment of the host)•Microbes are being used to clean up the oil spill in the Gulf of Mexico•Explains how microbial fermentation results in beer, wine, and breadMetabolism•Collection of controlled biochemical reactions that take place within cells of an organismMetabolic Processes Guided by Eight Elementary Statements•Every cell acquires nutrients•Metabolism requires energy from light or from catabolism of nutrients•Energy is stored in adenosine triphosphate (ATP)•Cells catabolize nutrients to form precursor metabolites•Precursor metabolites, energy, and enzymes are used in anabolic reactions to construct larger building blocks•Enzymes plus energy anabolically link building blocks in polymerization reactions•Cells grow by assembling macromolecules into cellular structures•Cells reproduce once they have doubled in sizeCatabolism and AnabolismOxidation and Reduction Reactions•Transfer of electrons from molecule that donates an electron to a molecule that accepts an electron•Reactions always occur simultaneously•Cells use electron carrier molecules to carry electrons (often in H atoms)•When electrons move from donor to acceptor, free energy is released (reducing power)–When electrons move from NADH to O2 during aerobic respiration, free energy is used to synthesize ATP•Three important electron carriers–NAD+ → NADH–NADP+ → NADPH–FAD FADH2→Oxidation and Reduction ReactionsATP Production and Energy Storage•Organisms release energy from nutrients; can be concentrated and stored in high-energy phosphate bonds of ATP•Phosphorylation – organic phosphate is added to substrate•Cells phosphorylate ADP to ATP in three ways–Substrate-level phosphorylation–Oxidative phosphorylation–Photophosphorylation•Anabolic pathways use some energy of ATP by breaking a phosphate bondATP Production and Energy StorageThe Roles of Enzymes in Metabolism•Catalysts – chemicals that increase the likelihood of a reaction but are not permanently changed in the process (organic catalysts = enzymes)•Naming and classifying enzymes–Most end with suffix –ase–Usually incorporate the name of the enzyme’s substrate•Over 1,000 enzymes exist in a single cell and each operates with extraordinary specificity and speed•Most are proteinsCarbohydrate Catabolism•Many organisms oxidize carbohydrates as the primary energy source for anabolic reactions•Glucose most common carbohydrate used•Glucose catabolized by–Cellular respiration (aerobic or anaerobic)–FermentationCarbohydrate Catabolism[INSERT FIGURE 5.12]Steps in Cellular Respiration1. Entry Mechanisms2. Catabolism 3. Biosynthesis4. Polymerization5. AssemblySteps in Cellular Respiration – Entry Mechanisms•Raw materials (such as glucose) must be brought into the cell•Sufficient concentrations of substrate must be maintained•Barriers must be overcome–Outer membrane–Prevents passage of hydrophilic & hydrophobic molecules–Diffusion of all substrates through porins–Cell wall–Loose molecular mesh which does not present significant barrier to nutrient passage–Cytoplasmic membrane–Prevents passage of hydrophilic compounds–Permeases bind substrate and carry it across the membrane–Some molecules enter via facilitated diffusion–Most enter via active transportSteps in Cellular Respiration – Entry Mechanisms•Sequences of biochemical reactions, each catalyzed by a different enzyme, that convert substrates into smaller molecules•Enzyme-catalyzed reaction sequences that transform substrate molecules (e.g. carbohydrates) into precursor metabolites, ATP, and reducing power–Glycolysis–Krebs Cycle–Pentose Phosphate Pathway–Entner-Doudoroff PathwaySteps in Cellular Respiration - CatabolismSteps in Cellular Respiration - Catabolism•Precursor Metabolites•Reducing Power–Oxidation-reduction reactions transfer protons plus electrons (transfer of H atoms)–H atoms are transferred to or from NAD+ or NADP+–NAD+ → NADH–NADP+ → NADPH–Reduced forms stores cell’s reserves of H atoms or reducing power–Reducing power used to–Reduce metabolic intermediates–Generate molecules of ATPSteps in Cellular Respiration - CatabolismSteps in Cellular Respiration - Catabolism•ATP–Always formed by adding a single phosphate group to ADP and this can be accomplished by–Substrate Level Phosphorylation–Oxidative Phosphorylation–PhotophosphorylationSteps in Cellular Respiration - Catabolism•Substrate Level Phosphorylation–ADP obtains a phosphate group attached to a metabolic intermediate by a high-energy bondCopyright © Gary E. KaiserSteps in Cellular Respiration - CatabolismOxidative PhosphorylationSteps in Cellular Respiration - Catabolism•Oxidative Phosphorylation–ATPase that catalyzes the formation of ATP from ADP through series of chemical events that occur in and around a membrane–In prokaryotes the ETC is located in the cytoplasmic membrane–In eukaryotes the ETC is located in the membrane of the mitochondria–In photosynthetic organisms the ETC is located in the membrane of the thylakoid–Energy needed for ATP formation is a concentration gradient formed across the membrane–Ions actively