Case Study: The world wide distribution of lactose intolerance

1. Stanford University:Shyamala Malladi Patricia Seawell Case Study: The world wide distribution of lactose intolerance University of Kentucky: Andrew Bouwma Peter Mirabito Jeffrey Osborn University of Miami: Douglas L. Crawford Marjorie F. Oleksiak Facilitators:Kimberly Tanner, San Francisco State Univ.Langdon Martin, Univ Wisconsin

2. Classroom Setting • Sophomore Genetics Course • Students have been introduced to GenesMolecular Mechanisms of TranscriptionTranscriptional RegulationMolecular Mechanisms of TranslationTranslational Regulation

4. Learning Goal6) Genotype  Phenotype7) Engagement in the Scientific Process Outcomes: • Interpret the biogeographical maps • Read and apply appropriate information from the primary literature to address a scientific problem. • Students will explain why specific populations maintain the ability to drink and digest milk through adulthood.

5. What do you think is the percentage of adults around the world who are lactose intolerant? A:0-20% B: 20-40% C: 40-60% D: 60-80% E:>80%

6. Lactose and Lactose Intolerance • Lactose is milk sugar, a disaccharide in all mammalian milk • Lactose intolerance is the inability to digest lactose, because of a lack of the required enzyme lactase in the digestive system. • Drinking milk without having an active lactase enzyme produces gastro-intestinal distress (e.g.,diarrhea). • It is estimated that 75% of adults worldwide show lactose intolerance.

7. Adult Worldwide Milk Intolerance due to the Inability to Digest Lactose Milk Intolerance Native Americans Aboriginal Australians Adapted from http://en.wikipedia.org/wiki/Lactose_intolerance

8. Adult Worldwide Lactose Intolerance Milk Intolerance What do these data say about the worldwide distribution of the ability to drink and digest milk as an adult? Think & Write 1 minute Pair-Share 2 minutes

9. Predict What would you predict is the relationship between the world wide distribution of adult and infant lactose intolerance? A: Same B: Opposite C: Unrelated D: Same except for North America Milk Intolerance

10. Discuss Convince your neighbor and revote What is the relationship between the world wide distribution of adult and infant lactose intolerance? A: Same B: Opposite C: Unrelated D: same except for North America

11. What is the relationship between the world wide distribution of adult and infant lactose intolerance? Frequency of Lactose Intolerance in Infants Milk Intolerance >90% Tolerance

12. Brainstorm Given these data: 75% of adults worldwide cannot drink and digest milk Yet nearly all infants are able to digest milk Propose molecular mechanisms to explain why only a few populations have the ability to drink and digest milk throughout adulthood.

13. Choose a hypothesis The molecular mechanism that explains why only a few populations have the ability to drink and digest milk throughout adulthood includes variation in: • A: the coding region of the lactase gene • B: the regulatory region of the lactase gene • C: transcription factors • D: the post-translational modification of the enzyme lactase • E: None of the above

14. For your final assessment • Read the Genetics paper on “Lactose Intolerance” • Write a short essay (250 words) to defend one hypothesis and refute one other > Paper will be posted on Blackboard. > Potential hypotheses will be posted. > Biogeographic map will be posted.

15. Diversity: Not using red-green map colors Population diversity Teaching methods addresses a diversity of learning styles Possible discussion of “Got Milk”