LiverEnzymeLabPurpose:Howwillenzymeactivitybeaffectedbymanipulatingindependentvariables?BackgroundInformation:Ineachindividualcellofahumantherearemanychemicalreactionstakingplace,performingthenecessaryfunctionsforbeingalarge,complex,multicellularorganism.Thisisrelativelyeasytounderstand.Howdothesereactionsoccur?Thisisnotsoeasytounderstand.Chemicalreactionsinvolvethebreakingandreformingofchemicalbondsbetweenmolecules(substratesorreactants),whicharetransformedintodifferentmolecules(products).Somechemicalreactionscanoccurspontaneously.Meaning,thechemicalreactioncanoccurwithoutanyaddedenergyorintervention.Whilecertainchemicalreactionsoccurspontaneously,otherchemicalreactionscannotandinstead,involvespecificmetabolicpathwaysforthereactiontohappen.Enzymesarebiologicalproteincatalysts.Theyhelptoincreasetherateofchemicalreactions.Enzymesaremostoftenproteinsandtheirthree-dimensional(3-D)shapeisimportanttotheircatalyticactivity.Becauseoftheir3-Dshape,enzymesarehighlyspecificforthereactionstheycatalyze.Enzymeactivityandeffectivenessisinfluencedbymanyfactors.First,enzymeactivitymaybenegativelyaffectedbychangesintemperature.Normally,enzymesworkataparticulartemperatureoptimumandifthetemperatureiseithertoohighortoolow,theenzymeactivityisreduced.Sinceenzymesareproteins,enzymeactivityisalsoaffectedbychangesinpH(measureofacidity).IfthepHchangesaretoodrastic,enzymescanbecomedenaturedandtheiractivityisreducedoreliminated.Lastly,enzymeactivitycanbeaffectedbyconcentration.Concentrationreferstohowmuchoftheenzymeispresent.Inthislab,youwillbeconductingaseriesofexperimentstolookathowenzymeactivityisaffectedbychangesintemperatureandpH.Theenzymeusedinthisexperimentiscalled,catalase.Catalaseisfoundinmanycellsbutisinhighestlevelsintheliverbecausetheliverfunctionstobreakdowntoxinspresentintheblood.Further,catalaseisresponsibleforbreakingdownhydrogenperoxide(H2O2)andproducesoxygengasandwater.Asthereactionoccurs,bubblesform,indicatingthathydrogenperoxideisbeingbrokendowninwaterandoxygengas.Themoreactivetheenzyme,themoreoxygen(andwater)itproduces.Thespecificchemicalreactionthatwewillbestudyingisthedecompositionof6%hydrogenperoxideintowaterandoxygengas.Theformulaforthereactionisasfollows:

2H2O2Catalase2H2O+O2 HydrogenPeroxideWaterOxygenPRELABQuestions:Youdonothavetowriteoutthequestions,BUTyoudohavetoanswerincompletesentences.

1. Whatarethefourmacromoleculesandwhichmacromoleculeareenzymes?2. Whatisthefunctionofenzymesandwhyaretheyimportantforourcells?3. Writedowntheequationfortoday’slabanddothefollowing:highlightthereactant(s)aboveyellow.

Highlighttheproduct(s)intheequationabovegreen.4. Whatindicationwillwehavethattheenzymeisworking(Hint:Lookattheproducts,whatwouldhave

thesetogetherlooklike?)5. Whatthreefactorswillaffecttheenzymeactivity?