MetabolismLearning objectives are to gain an appreciation of:Importance of MetabolismMetabolism: the bigger picturePowerPoint PresentationTwo parts of metabolismAnabolism and GrowthCarbons SourcesEnergy Sources:ATP and EnergyThe Role of ATP in MetabolismATP is produced by three processes:Chemical-based ATP synthesis:ATP synthesis by substrate-level phosphorylationEmbden Meyerhof Pathway a.k.a. glycolysisGlycolysis and FermentationSlide 17Slide 18Glycolysis and NADHNADHFermentationWhat is fermentation?Why is fermentation important?Slide 24Lactic Acid Fermentation: ILactic Acid FermentationLactic acid bacteria and dairy productsWhat happens to the lactate?Lactic acid bacteria are wasteful or are they?Substrates other than glucoseLarge complex polysaccharidesSome Complex PolysaccharidesPolysaccharides and Catabolic EnzymesMore energy can be conserved from glucose by oxidizing it to CO2Next LectureStudy QuestionsMetabolismPart I: FermentationsPart II: RespirationLearning objectives are to gain an appreciation of: •Catabolism and anabolism•ATP Generation and energy conservation•FermentationImportance of MetabolismImages: (1) www.bact.wisc.edu (2) en.wikipedia.org•Industrial–Yogurt, cheese–Bread, wine, beer•Medical/Health–Strain identification–Digestion•Environmental–Cycling of elements–Pollutant transformationMetabolism: the bigger picture•What is metabolism?–Chemical reactions that occur in living organisms in order to maintain life.•What does “maintain life” mean?–Growth and division–Maintaining cellular structures–Sense/respond to environment•Two parts of metabolism:–Cell componentsnutrients + C-source chemicals or lightTwo parts of metabolism•Anabolism- synthesis of complex molecules from simpler ones during which energy is added as input•Catabolism - the breakdown of larger, more complex molecules into smaller, simpler ones, during which energy is released, trapped, and made available for workAnabolism and Growth•Appropriate nutrients:–Carbon source–N, S, P sources–Trace metals•Appropriate environmental conditions:–pH–Oxygen–Temperature.–LightCO2AutotrophOrganic CompoundsHeterotrophAnabolism(biosynthesis)Carbons SourcesCatabolismOrganotrophsPhototrophsLitotrophsChemotrophsOrganic compounds,i.e., glucose, succinateInorganic compounds,S, Fe2+,CO2, H2, CH4LightChemical compoundsATP, pmfEnergy Sources:•Adenosine triphosphate•two of the phosphate bonds are high energy bonds •breaking bond to remove phosphate releases energyFigure 5.6ATP and EnergyThe Role of ATP in Metabolism•Reactions in which the terminal phosphate of ATP is removed results in a:•Exergonic breakdown of ATP can be coupled with:•Energy conserving reactions are used to catalyze the formation of ATP from ADP and Pi, and thus to restore the energy balance of the cellATP is produced by three processes:•_________________ phosphorylation–Two reactions are coupled to make ATP.•__________________ phosphorylation–Carried out by:–Requires:•PhotophosphorylationChemical-based ATP synthesis:Substrate level phosphorylationRespiration-linked phosphorylationADP obtains phosphate from metabolic intermediate•molecule which has a high energy bondATP is formedATP synthesis by substrate-level phosphorylation•Phosphorylated intermediates are generated in:–Glycolysis (Embden-Meyhof pathway)–Tricarboxylic Acid Cycle (TCA)–Fermentation•Finally, the Pi is transferred from a high energy phosphorylated intermediate to ADP by a kinaseEmbden Meyerhof Pathwaya.k.a. glycolysis•Major pathway for:•Major pathway of:•Widespread method of:•The end result is the release of a small amount of energy–conserved as ATP through:–And fermentation end products.Glycolysis and Fermentation•Glycolysis is an anoxic process•It is divided into two major stages•Nets two ATPs and two NADHs•End product of glycolysis is:•The fate of this metabolite varies:Energy InputReductionsATP by SLPGlucose + 6O2 6CO2 + 6H2O ∆G˚’= -2830 kJ/molGlycolysis and NADH•Glycolysis also generates NADH•But, cells need:•Fermentation can regenerate:–This can be done through:–Substrates can be reduced by NADHExample:Lactic acid fermentationNADHFermentationATP production by substrate level phosphorylationWhat is fermentation?•Widespread method of anaerobic metabolism•The end result is the release of a small amount of energy–conserved as ATP through substrate level phosphorylation•Incomplete oxidation of substrates•Need to have a fermentation balance–Oxidation-reduction state of products equal the substrates–NAD+ recycled•Fermentation end products are generally secretedWhy is fermentation important?•Ecologically important for decomposition of organic material in anaerobic environments•Byproducts are usually energy rich and used by other microbes as energy/carbon sources•Useful in food industry•DigestionLots of fermentable carbon sourcesSubstrate level PLactic Acid Fermentation: I•Carried out by several groups of bacteria–Lactobacillus and Lactococcus•Gram +•No cytochromes•Anaerobes•Only use sugarsLactic Acid FermentationKey ReactionFermentations have to maintain redox balance.Lactic acid bacteria and dairy products•These bacteria are used to to make cheese and yogurt from milk.•Carbon/energy source in milk is lactose•Lactose is hydrolyzed•Causes pH to decrease•Milk proteins coagulateQuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.http://web.mit.edu/esgbio/www/lm/sugars/lactose.gifQuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.http://www.reluctantgourmet.com/images/cheese.jpgWhat happens to the lactate?•Transported out by lactate symporter–Takes a proton out with it.•Lactate is still a good carbon/energy source.Glucose  2 Lactate ∆G˚’= -196 kJ/molMade 2 ATPs = +63 kJ/mol-133 kJ/mol left in lactateWasted energy!Lactic acid bacteria are wasteful or are they?•They live in organic rich environments without oxygen•They generate a proton gradient so more ATP can be made•They make acid which inhibits competitors•They can grow in low iron environmentsSubstrates other than glucose•Monosaccharides–Fructose, mannose, galactose get converted to glucose-6-phosphate or fructose-6-phosphate•Disaccharides--get cleaved in monosaccharides by specific enzymes–Lactose => galactose and glucose–Maltose => 2 glucoses–Sucrose =>