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1、BuffersSafetyPrecautionsSafetygogglesandglovesmustbewornatalltimesduringthisexperiment.Wewillbeusingstrongacidsandbaseswhichcancausesevereburnsandeyeinjuries;therefore,payattentiontohowyouhandlecontainersandhowyouaddandmixdifferentreagents.Washcontaminatedareaswithcoldwater.Reportanyspillstothe
2、instructor.BackgroundInformationBiochemicalprocessesonmolecularorcellularlevelsdependonstrictregulationofthehydrogenionconcentration.TheactivityofdifferentenzymesinourbodyvariesgreatlyasthepHoftheenvironmentchanges.Thenaturalconformationofmostbiomoleculesisafactorofextracellularorintracellularp
3、H.SignificantvariationsinpHcanresultinreversibleandirreversibledenaturationandinactivationofproteins.Therefore,toachieveoptimalcellularactivitythepHmustbekeptataconstantvalue.Thisisassuredbythepresenceofnaturallyoccurringbuffers.ThesebuffershavetheabilitytoresistpHchangesbasedontheirpKavalues.A
4、bufferconsistsofaweakacidinequilibriumwithitsconjugatebase.Therefore,ifanacidicagentisintroducedintotheenvironment,theprotonsreleasedbytheacidaretakenupbytheconjugatebaseandnodropinpHisobserved.Ifabasicagentisaddedtotheenvironment,theadditionalhydroxideionsareneutralizedbytheweakacid,thusthepHi
5、snotincreased.ThestorystandsuntiltheamountofH+orOH-addedtothesolutionovercomestheweakacidandbaseofthebuffer.Oncealltheweakacidandweakbaseareconsumedduetotheadditionofbaseoracidrespectively,thebufferingcapacityislost.Thebufferingsysteminourbloodstreaminvolvescarbonicacid/bicarbonateandCO2reactin
6、ginaclosedsystem.Experimentally,itisdifficulttousethisbufferingsysteminthelabduetothelossofCO2totheenvironment,whichinturnresultsinlossofbufferingcapacity.Inexperimentalanalysis,bufferssuchasHEPES(pKa=7.55),whicharecompatiblewiththenaturalbuffersinthebody,areusedtomimicthecellularenvironment.An
7、otherdifficultyinchoosingtherightbufferforabiochemicalexperimentisprovidingtherightconditionsunderwhichthebufferisexpectedtofunctionsuchastheconcentration,salteffect,andtemperatureofthesolution.Itisalsoimportanttokeepinmindthatsom
