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Faculty of Applied SciencesTULO / MSc Science Education and Communication

Web chemistry: Sweeteners

Sec. education advanced levelScience on Stage, Grenoble, April 5th 2007

Aonne Kerkstra-Teacher at ISW in Naaldwijk-Specialist in chem. education

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Developing team (2004 – 2006)

•Teachers•Lovina Hofmeyer•Sylvia Lipman•John Hukom

•Experts (University of Amsterdam)•Nataša Brouwer, senior consultant for science education •Laurens Hessels, student-assistant •Diederik Slob, site tool en graphical design•Jan van Maarseveen, associate professor •Hens Borkent, Molecule Model Maker tools (Radboud University Nijmegen)

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Chemistry between context and concept• Appealing context

(Sweeteners is part of daily live)

• Basic concepts• All matter consist of particles

(Sweeteners consist of bio-organic molecules)

• Micro-macro concept: relationship between structure and property (taste)

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Web chemistry: Sweeteners

• Homepage• Introduction Sweeteners• Stereochemistry• Synthesis of Aspartame• Molecular structure en taste• Further investigation• Teachers manual

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1 Sweeteners• Key questions

•What is the difference in sweetness between natural, extensive and intensive sweeteners? •To which chemical compounds do sweeteners belong? •How much sweeter than sugar is aspartame?

•Structure web page•Introduction•Explanation•Information via links•Activity•Checkpoint 1

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2 Stereochemistry•Key questions

•How can you present structural formulas? •What does the 3D model of aspartame look like? •When do we call a carbon atom asymmetric? •What are the conditions for optical isomerism? •How can you measure optical activity?

•Structure web page•Introduction•Explanation•Assignments with 3D models•Questions with the molecule model maker•Further information via links•Activity•Checkpoint 2

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3 Synthesis of aspartame• Key questions

• What are the building blocks of aspartame? • What about the stereochemistry of the building blocks of aspartame? • How do you recognize the L- or D-configuration in amino acids? • How many and which stereo isomers does aspartame have? • Which reactants are used for the synthesis of aspartame? • What is the role van the enzyme in this synthesis? • How do you investigate the synthesis of aspartame?

• Structure web page• Introduction• Explanation• Assignments with explanation• More information via links• Questions• Activity • Checkpoint 3

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4 Molecular structure and taste• Key questions

• Hoe does taste transfer work? • What is a papilla? • Which type of building blocks are used in the taste receptor? • Which model can explain the operation of the sweet receptor? • Which non-covalent interactions are important? • How come the enantiomers of aspartame taste different?

• Structure web page• Introduction• Explanation with exercises• Assignments with explanation• Activity• Checkpoint 4

• Interaction with biology

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5 Further investigation• How do the different taste receptors work? • Explain what the R- and S- configurations are?• Aspartame investigation in several light soft drinks.• Design a new sweetener.• Investigate the stability of aspartame.• What happens to aspartame once it is ingested?• Aspartame often gets negative publicity.

Design a concept map of all types of isomers.• Design your own soft drink.• Student’s own idea.

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Chemical ideas and skills 1Well known New to learn

H-bond between polar moleculesVan der Waals bond between Non-polar molecules(Polar) atom bondIon bondPeptide bond

Non-covalent interactions H-bond, interaction between polar groups in a molecule Van der Waals bond, interaction between non-polar groups in a molecule Ion bond, interaction between positive and negative ions in a molecule

Structural formulas en nomenclature of: Alkanes Alcohols Carbon acids Esters Amines Amino acids

DipeptidesEnzymes as a stereo specific catalyst

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Chemical ideas and skills 2Well known New to learn

Structure isomers (constitutional isomers)

Stereo isomers Chiral molecules (asymm. C-atom) Optical activity Enantiomers Diastereoisomers

General ICT skills Specific ICT skills E-learning 3D modeling Communication tool links for further information

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E-learning in Web chemistry: Sweeteners

• Question• How does the navigation support the students to get the

answers to the key questions?

• Navigation• 4 chemical units• several list pages

• Questions (a banc)• Resources• Concepts• Dictionary OC• Site map

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E-learning in Web chemistry: Sweeteners

• Question• Which e-learning activities take place (beside

reading)?

• Activities• using animations• making digital questions (feed back)• investigating 3D models

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E-learning in Web chemistry: Sweeteners

• Question• Which digital tools are used?

• Tools• Java applets with 3D models (Jmol)• Molecule Model Builders,also in

combination with the assignments • Digital questions in Hot potatoes• Internet external links• Resources (further information)• Search engine in the Dictionary OC• Web-log (open assignments)•

computer tool information resource feed back

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E-learning in Web chemistry: Sweeteners

• Question• What is the additional teachers material? • How do the teachers communicate with each other?

• Teachers website• Digital teachers material:

• Didactic handbook • Experiments: materials, outcomes, tips

• Publish• Students work (assignments “open projects”)• Best practices (intern)• Tips & tricks • Share materials (intern)

• Give suggestions for improvements • web-log Contextchemie

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http://www.contextchemie.nl/en

Further information of contacta.kerkstra@tudelft.nl