By: Mandy Butler, Ying-Tsu Loh and Cheryl Ann Peterson SNPing Lactose By: Mandy Butler, Ying-Tsu Loh and Cheryl Ann Peterson

Three college students walk in an ice-cream bar. One orders a delicious 100% whole milk milkshake, the other two orders a Tofutti strawberry smoothie. Why?

LACTOSE (pre-assess student understanding) Lactose, the primary sugar in milk, is hydrolyzed by an enzyme called lactase. Virtually all humans are born with ability to utilize lactose but many lose ability to digest lactose by 12 or 13 years old. In lactose tolerant individuals, lactase gene is expressed into adulthood, so eating a milkshake is a pleasant experience. But in people who are lactose intolerant, that lactase gene is switched off after weaning, and the consumption of milk products can lead to unpleasant effects.

Pre-assess students on SNPs Scientists found a SNP in gene in the Finnish that seems to be correlated with lactose tolerance.

Examine phenotype vs genotype to find any correlation Which variant(s) are correlated with lactose tolerance? What is the dominant phenotype of the Finnish population?

What is the percentage of the genotype of the total Finnish population?

What is your conclusion from looking at the tables?

How could a SNP change the phenotype of an individual? Obtain some hypotheses or conclusions

Allele Frequencies from NCBI

ALlele FREquency Database   

Go to HAPMAP / ALFRED to examine non-Finnish populations Link to articles or have students find articles associated with the study. Examine DATA set Go to HAPMAP / ALFRED to examine non-Finnish populations What is the genotype frequency at this locus Are these populations lactose tolerant

LAB Generate primers – have students BLAST the primers to find the sequence that should be amplified Enter “WebCutter” (Biology Workbench) to find RE that can cut the sequence Determine the sizes that are produced in either genotypes Correlate Genotype with Phenotype