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Exploring Genetic Variation in a Caffeine Metabolism Gene




Yvelande Zephyr and Susan Walsh



This laboratory unit illustrates the core concept of genetic variation by having students analyze a single nucleotide polymorphism (SNP) from their own DNA, and can be scaled up or down to meet the needs of majors and nonmajors alike. Briefly, DNA is isolated from cheek cells, and a specific region of the CYP1A2 intron is amplified via PCR. Restriction fragment length polymorphism (RFLP) analysis is then used to detect the SNP,which is visualized with gel elecrophoresis. Students can generate a hypothesis based on their own behavior, test it, and interpret the results. Overall, this series of laboratories exposes students to a variety of basic molecular biology techniques, correlates to an observable phenotype without causing serious health concerns, and caters to students’ innate desire for self-discovery.

Genetics Concept(s) Addressed:

Nature of genetic material: What are the molecular components and mechanisms necessary to preserve and duplicate an organism’s genome?

Genetic variation: How do different types of mutations affect genes and the corresponding mRNAs and proteins?

Core Competencies Addressed:

Students should be able to implement observational strategies to devise a question.

Students should be able to generate testable hypotheses.

Students should be able to design an experiment using appropriate controls and appropriate sample sizes.

Students should be able to gather and evaluate experimental evidence, including qualitative and quantitative data.



Intermediate undergraduate (beginning undergraduate option); biology/genetics majors (nonmajors option)

Activity Type:

Inquiry-Based Laboratory Exercise

Activity Length:

2 four-hour lab periods (3 to 4 three-hour lab period options)



PCR, RFLP, caffeine, genetic testing, genetic variation




Zephyr, Yvelande and Walsh, Susan (2015). Exploring Genetic Variation in a Caffeine Metabolism Gene. Genetics Society of America Peer-Reviewed Education Portal (GSA PREP): 2015.001; doi:10.1534/gsaprep.2015.001



Resource Justification and Instructor Guide


Inclusive List of Instrumentation and Reagents


Majors Laboratories

Part 1 - Full (PDF, Word)

Part 1 - Shortened (PDF, Word)

Part 2 (PDF, Word)

Nonmajors Laboratories

Part 1 (PDF, Word)

Part 2 (PDF, Word)

Part 3 (PDF, Word)

Part 4 (PDF, Word)