Lactose Intolerance Series Session 1
Genes, Mutations, and Inheritance

Make the connection between DNA and traits, and understand basic principles of heredity.

Build a model to show how the genetic code is used to make proteins that give us traits like eye color and lactase persistence. Next, examine Gregor Mendel’s laws of heredity and use Punnet squares to show how genes are passed down from biological parents to offspring. Apply Mendel’s laws to create fictitious creatures, predict the genotypes and phenotypes of the next generation, and learn how corn can be used as a model to predict genotypes within a “population.” Explore how these concepts can be used to understand the connection between genetic variation and human health, focusing on mutations that promote lactase expression later in life.

Lactose Intolerance Series Session 2
Lactase Enzymes in Action

Observe the action of lactase and demonstrate how it can be manufactured in a lab.

Build a “bioreactor” where lactase enzyme is used to remove lactose from milk, replicating the industry process used to produce some lactose-free products. Test the milk’s glucose levels as the reaction progresses, demonstrating that enzymes continue to convert reactants into products over time.

Genetically engineer lactose intolerant bacteria with the lactase gene, and observe enzyme activity as the bacteria grow. This experiment illustrates the direct link between an organism's genotype and phenotype, and demonstrates how genetic engineering can be used for industrial enzyme production or gene therapy. Following overnight incubation, transformed bacteria can be compared to control bacteria for their ability to digest lactose, as seen by a color change.

Lactose Intolerance Series Session 3
Our Genes and Lactose Intolerance

Use your own DNA to analyze the most common genetic variations that lead to lactase persistence.

Most individuals who are able to digest lactose into adulthood—often called “lactase persisters”—have a mutation in the MCM6 enhancer region, located upstream of the lactase gene. The enhancer region controls expression of the lactase gene. In mammals, it is usually coded to stop expression after the nursing phase of life. There are at least five separate MCM6 mutations that have evolved independently in different parts of the world, but they all have the same effect—lactase production persists later in life.

Extract your own DNA from cheek cells and amplify the MCM6 enhancer region by Polymerase Chain Reaction (PCR), then learn how to use bioinformatic tools to determine if you have an allele for lactase persistence*. Explore how the combination of culture and natural selection has caused a genetic shift in certain human populations.

*Sequence results for this lab and written instructions for analysis will be sent to educators within one week of completion of this training.

These workshops are appropriate for Life Science, Genetics, and Biology teachers. The experiments can be connected to the new Life Science Regents investigation on lactose intolerance, and many of the concepts are also applicable to other areas of biology learning. Guided by a DNALC educator, training will focus on lab skills and conceptual connections.

Election Day PD
DIY your PCR: Purifying Taq Polymerase to Detect a Jumping Gene

Learn how to purify the Taq polymerase enzyme from engineered E.coli, and then use it to carry out an interesting human DNA analysis.

Our genome is largely made of non-coding DNA, nearly half of which consists of inserted elements called transposons, or jumping genes. These small DNA sequences can “jump” around in our genome using transposase enzymes that copy and paste the transposons at random. One jumping gene sequence called Alu has over a million insertions in our DNA. This lab focuses on one locus of chromosome 16, where a recent Alu insertion event created a variable region where some individuals have the insertion, but others do not.

In this lab, Polymerase Chain Reaction (PCR) and agarose gel electrophoresis will be used to visualize participant genotypes. PCR is a technique used to produce billions of copies of a target DNA sequence. Because the process requires high heat, it uses a heat-stable enzyme from the thermophilic bacterium Thermus aquaticus, called Taq polymerase. Participants will first extract and purify Taq polymerase from engineered E.coli, then use the “homemade” enzyme to amplify DNA obtained by cheek swab to determine the presence or absence of the chromosome 16 Alu insertion.

Participant data will act as a jumping-off point to discuss the bottleneck effect of genetic drift, which will be visualized with both hands-on and digital simulation activities. This will guide a subsequent discussion on genetic markers acting as molecular clocks, the global distribution of Alu, and how the Hardy-Weinberg Equilibrium can be applied to class data.

Teachers of Life Science, Biology, AP Biology and related courses are welcome to join this workshop. Guided by a DNALC educator, training will focus on lab skills and conceptual connections. There is no charge to attend.