Author: Dori L. Hess
Source: This material is based upon work supported by the National Science Foundation under Grant No. EEC-1161732. This lesson was developed based on an online report that different lactase supplements have different activity (https://www.consumerlab.com/reviews/lactose-free-milk_lactase-enzyme-supplement-review/lactose-intolerance/). The demonstration of enzyme specificity using lactase to break down lactose is a common biology lab, an example can be found here (http://www.learnnc.org/lp/pages/3398). This lesson expands on this basic property of lactase to compare the effectiveness of different lactase supplements.
Lactose intolerance is the number one known enzyme deficiency, with over 70% of the worlds (adult) population affected. According to the Encyclopedia of Children’s Health (http://www.healthofchildren.com/C/Carbohydrate-Intolerance.html) there are 30 to 50 million Americans who suffer from Lactose Intolerance. In this lesson, students will conduct a comparative study to examine the effectiveness of Lactase supplements versus pure Lactase? The lesson is presented as an inquiry lesson, but the attached worksheet provides guided instructions.
What should students know as a result of this lesson?
What should the students be able to do as a result of this lesson?
Lactase supplements these items can be purchased at a local drug store, grocery store, or online retailer.
Glucose and sucrose can be purchased from chemical suppliers like Flynn scientific (Glucose is also commonly sold as dextrose).
Show students a video on lactose intolerance https://www.youtube.com/watch?v=1Pe5a4C6KmY is one suggestion.
Demonstration on lactose intolerance: This demonstration should be done prior to the lab. After conducting the demonstration, allow students to develop their own procedures to comparatively study several lactase supplements. http://www.flinnsci.com/store/Scripts/prodView.asp?idproduct=19009&noList=1
For teachers who prefer not to carry out this lesson as a guided inquiry lab, follow the procedure on the worksheet.
Students are required to recognize and analyze explanations and models and use data from the models in order to support a scientific argument.
After completing this lab (either as a guided lab or inquiry based), students will be able to see how enzymes function in the body and they will have a model to use in order to argue that man-made supplements work (or don’t work) just as well as natural enzymes. By formulating an explanation based on logic and evidence, this helps students to develop critical thinking skills.
This article discusses the genetics behind lactose intolerance and can be used as an extension to the lab and a route to tie in the students: http://www.news.cornell.edu/stories/2005/06/lactose-intolerance-linked-ancestral-struggles-climate-diseases.
This lab allows students to investigate lactose intolerance, natural selection and evolution: https://science.education.nih.gov/supplements/nih10/evolution/lesson2.html.
Students may want to explore other enzymes that may be involved in metabolic disorders by investigating how pH and temperature affects the enzyme function. Several enzyme disorders can be found at: http://enzymes.subtleenergysolutions.com/enzyme-deficiency.html.
Common Core Standards:
All lab safety rules should be followed. Make sure to read all MSDS material for the chemicals used in the lab.
Lactose Intolerance is not an uncommon disorder. This lesson provides students with the opportunity to explore the effectiveness of oral lactase supplements versus natural and decide for themselves, which product works best.
Teachers may choose various routes to assess their students. Traditional assessments could include: Lab Report or Student presentation on the lab and their results.
This is an online rubric that can easily be used for this lab: http://mccam.weebly.com/lactase-lab-rubric.html.
Grouping Suggestions: Lactase works best at a pH of 6. Students may be placed into groups of 3 or 4, but it is best to assign duties when larger groups are used.
Pacing/Suggested Time: 2 ninety minute class periods are suggested for the inquiry based option of this lesson. Teachers who conduct the guided lesson, may choose to use 1 or 2 ninety minute class periods. Students may design a study to check for lactose levels in items like sodium caseinate or other milk derivatives.