Integrating Lecture,

Laboratory, and Literature using Case Studies

Ann T.S. TaylorChemistry Department

Wabash CollegeCrawfordsville, IN 47933

What are your non-content

course goals?

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The Context: Che 361

• Required course for Chemistry majors

• Most Chem minors also take the course

• Organic II prerequisite

• Typical enrollment: 24-30 students, 8-12 per lab section

• Three 50 minute class periods and one three hour lab per week

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Che 361: Biochemistry non-content goals

• Cooperative learning strategies

• Transferrence and connections

• Application, not only memorization

• Cultivate intellectual curiosity

• Requires critical thinking skills

• Oral and written communication skills

• Use bioinformatic and modeling tools

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Common features my cases

• A short real-life story

• Reading review and primary literature articles

• Short in-class small group activities which connect the case and lecture

• Laboratory activities that directly relate to the case

• Computational activity

The Case of the Tainted Tacos

A Case Study on Genetically Modified Foods which integrates laboratory,

lecture, and literature

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Unit goals

Students should be able to:• Explain transcription and translation• Design PCR probes for a sequence of interest• Understand how transgenic organisms are made• Reinforce principles of enzymology, protein

structure, and membrane transport• Resolve conflicting data sets• Understand the broader ethical implications of

using GM foods

The Case of the Tainted Tacos

The Setup Story

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Questions generated by story

• How are GM foods made?• How do GM foods “work”?• Are GM foods safe for the environment?• Could weeds become resistant to herbicides?• Are GM foods safe for humans?• Do farmers really benefit from using GM

products?• Should I eat GM foods? Do I already eat GM

foods?

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Case teaching strategies

• Common study areas

• Specialization

• Jigsawing

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Questions all groups study

• What are the most common genetic modifications of foods

• How genetic modifications are made

• How genetic modifications can be detected, and how these methods work

• Design the primers that are used in the lab

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Specialist groups

Farmers• Study the economic impact of GM foods and

how RoundUp Ready products work

Entomologists• Study the mechanism of Bt products and their

impact upon other insects

Immunologists• Look at methods to predict allergenicity

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Linking Literature

• Guided reading questions

• Small group problems

• Literature searches

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Example: Farmers

Read three papers, then answer questions such as:• Why do farmers use genetically modified plants? • When do farmers benefit economically from using GM

crops? • Why does RoundUp (glyphosate) affect plants but not

animals? • How does glyphosate affect EPSPS, both structurally

and kinetically? • Describe in detail how weeds that are resistant to

RoundUp differ from wildtype (normal) plants.

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Economic impact of GM crops

Goals:• Better pest

management• Increase yield• Reduce pesticide use• More flexibility

Disadvantages:• Only profitable when

infestation cost is greater than tech cost

• Unknown effect on soil ecology

• Development of “superweeds”

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How does RoundUp work?

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Integrating technology

• Presentations

• Research techniques with guided directions

• Tools and tutorials from the internet

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RoundUp Resistance modeling

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Entomologist modeling

Protein Slope of short circuit current decay

Wild type (no mutation)

-13.8

R224A -10.2

R228A -9.6

R233A -4.2

No cry protein 0

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Computational analysis of Cry9 for allergenicity

• Does it have homology to known allergens?– BLAST search of allergen database– STGSST (422-428) is identical to a sequence

in a Aspergillus fumigatus allergen

• Is the homology in a hydrophilic region?– No—from a computational tool discussed in

one of the papers

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Linking lab

Do an experiment related to the issue!• Sources:

– Adapt an existing lab– Adapt a “real world” technique– Adapt an experiment from one of the papers– Adapt a published teaching lab (Biochemistry and

Molecular Biology Education, Journal of College Science Teaching, Journal of Chemical Education)

• Work on the case during lecture and lab

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Typical lab results

• Lane 1, Arrowhead Mills corn meal; lane 2, Kroger corn meal; lane 3, Quaker white corn meal; lane 4, Cotton Pickin’ corn muffin mix; lane 5, Jiffy corn muffin mix; lane 6,Gold Medal corn muffin mix; lane 7, Aunt Jemima corn bread mix; lane 8, Martha White corn muffin mix; lane 9, non-transgenic corn seed; lane 10, Pioneer YieldGard corn seed.

1 2 3 4 5 6 7 8 9 10

20001000

500300200

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Break down of events

Lecture Laboratory Case-Nucleic acid structure

-Transcription and translation

-Nucleic acid methods

-Isolate DNA from food samples

-Determine DNA purity (A260/A280 )

-Set up PCR

-Read set-up story

-Divide into teams

-Read common and specialist papers

-Recombinant DNA methods

-Making transgenic plants

-Analyze PCR results via agarose gel electrophoresis

-Group presentations

-Ethics discussion

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Other examples

• Olestra case – http://www.providence.edu/chm/kcornely/Cas

ebook.htm– extract & digest lipids from potato chips

• Drug discovery– HIV protease kinetic analysis – structure exploration– Drug discovery lab (BAMBED (2005) 33:

16 – 21)

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References

• Case study:– Advanced version:

http://www.sciencecases.org/gmo/gmo_adv.asp– GOB version:

http://www.sciencecases.org/gmo/gmo_gen.asp– Also published in JCST (2005) 34(2):

• Lab experiments:– Taylor, J Chem Ed (2005) 82 (4): 597-598.– Brinegar & Levee BAMBED (2004) 32: 35-38. – http://www.greenomes.org/

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Case study collections

• https://chico.nss.udel.edu/Pbl/ (requires password)

• http://www.fhs.mcmaster.ca/pbls/writing/• http://ublib.buffalo.edu/libraries/projects/ca

ses/ubcase.htm

• K. Cornely, Cases in Biochemistry, John Wiley & Sons, 1999; also at http://www.providence.edu/chm/kcornely/Casebook.htm