Lec1-Introduction-st.ppt

Biochemistry Autumn2012GeneralInformation Instructor ZhiZhu email zhuzhi Text Lehninger PrinciplesofBiochemistry 3rdEd JingyanWangetal Biochemistry 3rdEdScore 90 exam 10 quiz question 50 50 MeetingTimes M10 10am 11 50am R8 00pm 9 40pm everyweek WonderofLife Hierarchyofmolecularorganizationinacell WhatIsBiochemistry Seekstodescribethestructure organization andfunctionsoflivingmatterinmolecularterms Thestructuralchemistryofthecomponentsoflivingmatterandtherelationshipofbiologicalfunctiontochemicalstructure Metabolism thetotalityofchemicalreactionsthatoccurinlivingmatter MolecularGenetics thechemistryofprocessesandsubstancesthatstoreandtransmitbiologicalinformation RootsofBiochemistry Thepresentdaybiochemistryistheinterweavingproductofhistoricaltraditionsofbiochemistry cellbiology andgenetics Flemming sdiscoveryofchromosomes 1875 Miescher sisolationofnucleicacids 1869 Mendel scharacterizationofgenes mid 1800 Buchners fermentationofsugarfromyeastextracts 1897 WatsonandCrick sstructureofDNA 1953 Wohler ssynthesisofurea 1828 Organicchemistry whichdescribesthepropertiesofbiomoleculesBiophysics whichappliesthetechniquesofphysicstostudythestructuresofbiomoleculesMedicalresearch whichincreasinglyseekstounderstanddiseasestatesinmoleculartermsNutrition whichhasilluminatedmetabolismbydescribingthedietaryrequirementsformaintenanceofhealth BiochemistryDrawsItsMajorThemesfrom Microbiology whichhasshownthatsingle celledorganismsandvirusesareideallysuitedfortheelucidationofmanymetabolicpathwaysandregulatorymechanismsPhysiology whichinvestigateslifeprocessesatthetissueandorganismlevelsCellbiology whichdescribesthebiochemicaldivisionoflaborwithinacellGenetics whichdescribesmechanismsthatgiveaparticularcellororganismitsbiochemicalidentity BiochemistryDrawsItsMajorThemesfrom DistinguishingCharacteristicsofLivingMatter ConstantrenewalofahighlyorderedstructureaccompaniedbyanincreaseincomplexityofthatstructureDegreeofcomplexity thousandsofdifferentmoleculesmakeuptheintricateinternalstructuresinacell Microscopiccomplexityandorganizationareapparentinthiscolorizedthinsectionofvertebratemuscletissue viewedwiththeelectronmicroscope BiochemistryasaChemicalScience BiologicalMolecules Monomer Polymer BiologicalMolecules Polysaccharidesservebothasstructuralcomponentsandasreservesofbiologicalenergy Nucleicacidsparticipateininformationstorage transmission andexpression Proteins 1 Performstructuralrolesinthebody 2 Actastransportsubstances 3 Defendanorganismagainstinfection and4 Functionasenzymes catalyzingthethousandsofchemicalreactionsthatoccurwithinanindividualcell Lipidsserveasthemajorstructuralelementofthemembranesthatsurroundcellsandpartitionthemintovariouscompartments Theyalsoarethemajorenergystorageformofcells NumerousDifferentBiomoleculesinaCell CellBiologyBiochemistry DiverseLivingOrganisms DistinguishingCharacteristicsofLivingMatter Livingorganismsextract transform anduseenergyfromtheirenvironment Theenergyenablesthemtobuildandmaintaintheirintricatestructureortodowork Aprairiefalconacquiresnutrientsbyconsumingasmallerbird Bioenergetics Alivingorganismmustworktostayaliveandreproducethemselves whichconsumesenergy Thiscomesto bioenergetics Bioenergeticsisaboutenergytransformationandexchange Thecentralissueisthemeansbywhichenergyfromfuelmetabolismiscoupledtoenergy requiringreactions Theyuseenergytoconcentrateionsfromtheirsurroundings forexample Theabsorptionofionsisanactiveprocessandconsumesenergy LivingOrganismsarenotatEquilibriumwiththeirSurroundings MolecularCompositionisataDynamicEquilibrium ALivingOrganismisanOpenSystem Aclosedsystem itexchangesneithermatternorenergywithitssurroundings Anopensystem itexchangesbothenergyandmaterialwithitssurroundings Livingorganismsuseeitheroftwostrategiestoderiveenergyfromtheirsurroundings theytakeupchemicalfuelsfromtheenvironmentandextractenergybyoxidizingthem theyabsorbenergyfromsunlight Solarenergy photosynthesis herbivores carnivores Inanyphysicalorchemicalchange thetotalamountofenergyintheuniverseremainsconstant althoughtheformoftheenergymaychange PrincipleoftheConservationofEnergy 在任何一种物理或化学变化中 尽管能量的形式可能发生改变 但整个体系中能量的总量保持不变 势能 能量转换而做功 环境中的营养成分 复杂分子如糖类 脂肪 阳光 细胞中的化学转换 细胞功能 化学合成机械功渗透压和电势梯度光产生遗传信息传递 热 环境中增加的无序性 熵 代谢产生比起始的燃料分子更简单的化合物 系统内减少的无序性 熵 简单化合物聚合形成信息丰富的大分子 DNA RNA 蛋白质 FlowofElectronsProvidesEnergyforOrganisms Allthesereactionsinvolvingelectronflowareoxidationreductionreactions 热核聚变 DGisthefreeenergychangebetweenthereactantsandproducts G H T S G0 endergonic EnergyCouplingLinksReactionsinBiology Keqand GoAreMeasuresofaReaction sTendencytoProceedSpontaneously G 0 WhenKeq 1 Goislargeandnegative WhenKeq 1 Goislargeandpositive Theactivationenergyofachemicalreactionistheenergyrequiredtoconvertthereactanttotransitionstate whichgivesrisetoproduct s EnzymesPromoteSequencesofChemicalReactions 1010 1014faster En2En3En4En5 Versatility Specificity AdjustabilityFeedbackInhibition CentralRoleofATPinMetabolism Catabolism degradative free energy yieldingreactionsAnabolism syntheticpathways invariablyrequiretheinputofenergyTheoverallnetworkofenzyme catalyzedpathwaysconstitutescellularmetabolism DistinguishingCharacteristicsofLivingMatter Thecapacityforpreciseself replicationandself assembly thequintessenceofthelivingstate Biologicalreproductionoccurswithnear perfectfidelity GeneticContinuityisVestedinDNA Sennacherib棱柱 亚述语2万字符50kg2700年 释放到大肠杆菌细胞外的单个DNA分子1千万字符不到10 10g数百万年 GeneticinformationisencodedinthelinearDNApolymermadeoffourdifferentmonomericsubunits deoxyribonucleotides DNAcanreplicatewithhighfidelityThedouble helixDNAmoleculehasthetemplateforself replicationandself repairing GeneticContinuityisVestedinDNA ChangesintheHereditaryInstructionsAllowEvolution Thegradualaccumulationofmutationsoverlongperiodsoftimeresultsinnewbiologicalspecies eachwithauniqueDNAsequence Themostfundamentalpropertyofevolvingsystemsistheirabilitytoreplicateorreproduce Withoutthisproperty moleculewillbesoonextinctionduetodegradation Asecondprincipleofevolutionisvariation Nochange noevolution Athirdbasicprincipleofevolutioniscompetition Competitionselectthebettervariants EvolutionRequiresReproduction Variation andSelectivePressure Intube thegenomeofbacteriophageQ asingleRNAstrandofabout3300bases Q replicase andprecursors Noselectivepressure exactlyreplication Underselectivepressure suchastime thecompositionofreplicatemoleculeschangedramatically ThePrincipleofEvolutioncanbeDemonstratedinVitro Decreasingthetimeavailableforreplicationfrom20minto5min Humanchromosomes containtheDNAmoleculesthatconstitutethehumangenome Diseaseandthegenome Adiagramofhumanchromosome7 withbandq31 2 ageneinthisregionencodesaproteinthat whenmalfunctioning causecysticfibrosis 囊性纤维化 属遗传性胰腺病 GeneMutationandDisease DNAEncodesProteinswith3DStructures CentraldogmaNoncovalentinteractionstabilizethe3Dstructure CovalentbondsarethestrongestNon covalentinteractionshavedramaticinfluenceonbiochemicalreactionsElectrostaticinteractionsHydrogenbondingvanderWaalsinteractionshydrophobicinteraction ChemicalBondsinBiochemistry Coulomb slawE kq1q2 Dr2E energyq1 q2 chargesofthetwoatomsD dielectricconstantk constant 332kcal molor1389kJ molr2 thedistancebetweenthetwoatoms Twooppositeatomsinwaterseparatedby3 hasenergy 1 4kcal mol 1 ElectrostaticInteractions Mg2 H2O Hydrogen bonddonor thehydrogenismoretightlylinked Hydrogen bondacceptor thehydrogenislesstightlylinked Hydrogenbondenergy 1 3kcal mol Thehydrogenatominahydrogenbondispartlysharedbetweentworelativelyelectronegativeatomssuchasnitrogenoroxygen 2 HydrogenBonds Energy 0 5 1 0kcal mol 3 vanderWaalsInteractions TwooxygenmoleculesinvanderWaalscontact Thebasis thedistributionofelectricchargearoundanatomchangeswithtime Thetransientasymmetryintheelectronicchargearoundanatominducesacomplementaryasymmetryintheelectrondistributionarounditsneighboringatoms Energyexistsastwoatomsapproachoneanother 4 HydrophobicEffects Astwosuchnonpolarmoleculescometogether someofthewatermoleculesarereleased andsotheycaninteractfreelywithbulkwater Hence nonpolarmoleculeshaveatendencytoaggregateinwaterbecausetheentropyofthewaterisincreasedthroughthereleaseofwatermolecules ProteinFoldingCanBeUnderstoodinTermsofFree EnergyChanges ThefoldingprocesscanoccurwhenthecombinationoftheentropyassociatedwiththehydrophobiceffectandtheenthalpychangeassociatedwithhydrogenbondsandvanderWaalsinteractionsmakestheoverallfreeenergynegative QuestionsAskedbyBiochemists Whatarethechemicalstructuresofthecomponentsoflivingmatter Howdotheinteractionsofthesecomponentsgiverisetoorganizedsupramolecularstructures cells multicellulartissues andorganisms Howdoeslivingmatterextractenergyfromitssurroundingsinordertoremainalive Howdoesanorganismstoreandtransmittheinformationitneedstogrowandtoreproduceitselfaccurately Whatchemicalchangesaccompanythereproduction aging anddeathofcellsandor