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Enzyme Structure and Function: Comparing Student Responses to Multiple Question Versions Tanner Foster, Kevin Haudek, Rosa Moscarella, Rachel Yoho, Mark Urban-Lurain, John Merrill Automated Analysis of Constructed Response (AACR) Research Group www.msu.edu/~aacr WHAT DOES AACR DO? WHY IS ENZYME BINDING IMPORTANT? WHY CONSTRUCTED RESPONSE (CR)? EXPLORATORY ANALYSIS OF QUESTION VERSIONS TEXTBOOK INFLUENCES EXPERT RESPONSE VS. STUDENT ANSWERS WHAT'S NEXT? • Our research group follows what we call a Question Development Cycle (QDC). • Our research questions are designed based on the discipline's big ideas, core concepts, of concept inventories. • The ultimate goal is to create models that can predict the human score. • Structure and function is one of 5 core concepts for Biological Literacy as stated by Vision and Change in Undergraduate Biological Education. • This concept is difficult for many students, and instructors affiliated with the project are interested in exploring student ideas. Constructed Response allows students to: • Express what they know in their own words (Kuechler and Simkin, 2010) • Highlight misconceptions they may have. • Inform instructors of what students do and do not understand (Birenbaum and Tatsouka, 1987) Version 1 (n=48) Enzymes help chemical reactions in living organisms. How would a molecular biologist explain how an enzyme molecule binds to its correct substrate and reduces the possibility of incorrect interactions? Version 2 (n=48) Enzymes help in chemical reactions in living organisms. How would a molecular biologist explain the mechanism that helps an enzyme to bind to its correct substrate and reduces the possibility of incorrect interactions? Version 3 (n=51) Enzymes help in chemical reactions in living organisms. There are thousands of different molecules in a cell. How would a molecular biologist explain the mechanism that allows an enzyme to bind to a correct molecule? References: American Association for the Advancement of Science. (2011). Vision and change in undergraduate biology education: a call to action. Washington, DC. Birenbaum, M., & Tatsouka, K. K. (1987). Open-ended versus multiple-choice response formats - It does make a difference for diagnostic purposes. Applied Psychological Measurement, 11, 329-341. Freeman, et al. Biological Science. 6th ed. 2017. Kuechler, W. L., & Simkin, M. G. (2010). Why is performance on multiple-choice tests and constructed-response tests not more closely related? Theory and an empirical test. Decision Sciences Journal of Innovative Education, 8(1), 55-73. Mason, et al. Understanding Biology. 1st ed. 2014. Acknowledgements: This material is based upon work supported by the National Science Foundation (DUE grants1323162, 1347740). Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the supporting agencies. • Present questions to larger sample size of students in similar courses. • Analyze responses to determine best question version(s). • Investigate if class level affects response variability. • Begin rubric development. AACR III COLLABORATING INSTITUTIONS Freeman: “Given that an enzyme’s structure is critical to its function, it’s not surprising that an enzyme’s activity is sensitive to conditions that alter protein shape.” (182) Mason: “By bringing two substrates together in the correct orientation or by stressing particular chemical bonds of a substrate, an enzyme lowers the activation energy required for new bonds to form. The reaction thus proceeds much more quickly than it would without the enzyme” (122) Instructors agreed that an expert level answer would include: • Three dimensional shape of the molecules • Mention of chemical properties affecting binding • Energetic aspect stating the correct interactions are most favorable Below are examples of student answers: Enzymes have a specific "lock and key" structure which is specific for that molecule. It makes sure that when the enzyme binds, it fits into the structure and then changes the molecule's structure to make sure nothing else binds on it. The substrate can bind to the enzyme by hydrogen or covalent binding. To reduce the possibility of incorrect interactions the enzyme has a specific shape that allows for binding to a specific substrate. There are two main mechanisms for enzyme binding. One is induced fit, where the substrate changes the conformation of the enzyme so it can bind. The other is the lock and key model, in which the substrate fits perfectly into the enzyme's binding site. Enzymes also have different affinities for different substrates. These three question versions were asked as post-instruction homework in an upper level Biochemistry at a large Midwestern Research University. We found that students responded similarly to each question version. However, their responses were mostly based on the thee- dimensional structure of molecules rather than on the energetics of their interaction.

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Page 1: Enzyme Structure and Function: Comparing Student …conference.create4stem.msu.edu/sites/default/files/papers/Tanner... · Enzymes help in chemical reactions in living organisms

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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.

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