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EnzymeStructureandFunction:ComparingStudentResponsestoMultipleQuestionVersions
TannerFoster,KevinHaudek,RosaMoscarella,RachelYoho,MarkUrban-Lurain,JohnMerrillAutomatedAnalysisofConstructedResponse(AACR)ResearchGroup
www.msu.edu/~aacrWHATDOESAACRDO?
WHYISENZYMEBINDINGIMPORTANT?
WHYCONSTRUCTEDRESPONSE(CR)?
EXPLORATORYANALYSISOFQUESTIONVERSIONS
TEXTBOOKINFLUENCES
EXPERTRESPONSEVS.STUDENTANSWERS
WHAT'SNEXT?
• OurresearchgroupfollowswhatwecallaQuestionDevelopmentCycle(QDC).
• Ourresearchquestionsaredesignedbasedonthediscipline'sbigideas,coreconcepts,ofconceptinventories.
• Theultimategoalistocreatemodelsthatcanpredictthehumanscore.
• Structureandfunctionisoneof5coreconceptsforBiologicalLiteracyasstatedbyVisionandChangeinUndergraduateBiologicalEducation.
• Thisconceptisdifficultformanystudents,andinstructorsaffiliatedwiththeprojectareinterestedinexploringstudentideas.
ConstructedResponseallowsstudentsto:• Expresswhattheyknowintheirownwords(KuechlerandSimkin,2010)
• Highlightmisconceptionstheymayhave.• Informinstructorsofwhatstudentsdoanddonotunderstand(BirenbaumandTatsouka,1987)
Version1(n=48)Enzymeshelpchemicalreactionsinlivingorganisms.Howwouldamolecularbiologistexplainhowanenzymemoleculebindstoitscorrectsubstrateandreducesthepossibility ofincorrectinteractions?
Version2(n=48)Enzymeshelpinchemicalreactionsinlivingorganisms.Howwouldamolecularbiologistexplainthemechanismthathelpsanenzymetobindtoitscorrectsubstrateandreducesthepossibility ofincorrectinteractions?
Version3(n=51)Enzymeshelpinchemicalreactionsinlivingorganisms.Therearethousandsofdifferentmoleculesinacell.Howwouldamolecularbiologistexplainthemechanismthatallowsanenzymetobindtoacorrectmolecule?
References:AmericanAssociationfortheAdvancementofScience.(2011).Visionandchangeinundergraduatebiologyeducation:acalltoaction. Washington,DC.Birenbaum,M.,&Tatsouka,K.K.(1987).Open-endedversusmultiple-choiceresponseformats- Itdoesmakeadifferencefordiagnosticpurposes.AppliedPsychologicalMeasurement,11,329-341.Freeman,etal. BiologicalScience. 6thed. 2017.Kuechler,W.L.,&Simkin,M.G.(2010).Whyisperformanceonmultiple-choicetestsandconstructed-responsetestsnotmorecloselyrelated?Theoryandanempiricaltest.DecisionSciencesJournalofInnovativeEducation,8(1),55-73.Mason,etal. UnderstandingBiology. 1sted. 2014.Acknowledgements:ThismaterialisbaseduponworksupportedbytheNationalScienceFoundation(DUEgrants1323162,1347740).Anyopinions,findingsandconclusionsorrecommendationsexpressedinthismaterialarethoseoftheauthor(s)anddonotnecessarilyreflecttheviewsofthesupportingagencies.
• Presentquestionstolargersamplesizeofstudentsinsimilarcourses.
• Analyzeresponsestodeterminebestquestionversion(s).• Investigateifclasslevelaffectsresponsevariability.• Beginrubricdevelopment.
AACRIIICOLLABORATINGINSTITUTIONSFreeman:“Giventhatanenzyme’sstructureiscriticaltoitsfunction,it’snotsurprisingthatanenzyme’sactivityissensitivetoconditionsthatalterproteinshape.”(182)
Mason:“Bybringingtwosubstratestogetherinthecorrectorientationorbystressingparticularchemicalbondsofasubstrate,anenzymelowerstheactivationenergyrequiredfornewbondstoform.Thereactionthusproceedsmuchmorequicklythanitwouldwithouttheenzyme”(122)
Instructorsagreedthatanexpertlevelanswerwouldinclude:• Threedimensionalshapeofthemolecules• Mentionofchemicalpropertiesaffectingbinding• Energeticaspectstatingthecorrectinteractionsaremost
favorableBelowareexamplesofstudentanswers:Enzymeshaveaspecific"lockandkey"structurewhichisspecificforthatmolecule.Itmakessurethatwhentheenzymebinds,itfitsintothestructureandthenchangesthemolecule'sstructuretomakesurenothingelsebindsonit.
Thesubstratecanbindtotheenzymebyhydrogenorcovalentbinding.Toreducethepossibilityofincorrectinteractionstheenzymehasaspecificshapethatallowsforbindingtoaspecificsubstrate.
Therearetwomainmechanismsforenzymebinding.Oneisinducedfit,wherethesubstratechangestheconformationoftheenzymesoitcanbind.Theotheristhelockandkeymodel,inwhichthesubstratefitsperfectlyintotheenzyme'sbindingsite.Enzymesalsohavedifferentaffinitiesfordifferentsubstrates.
Thesethreequestionversionswereaskedaspost-instructionhomeworkinanupperlevelBiochemistryatalargeMidwestern
ResearchUniversity.
Wefoundthatstudentsrespondedsimilarlytoeachquestionversion.However,theirresponsesweremostlybasedonthethee-dimensionalstructureofmoleculesratherthanontheenergeticsoftheirinteraction.