BI 102 - General Biology

Tabletop Lab – Toothpickase and Lactase instructions:

Lactose intolerance is a condition that affects many adults. Humans and other mammals are born with the ability to make the enzyme lactase, which is necessary to digest lactose, the primary sugar in milk. In most mammals, the gene that produces the lactase enzyme is turned off after infancy. In humans, however, especially humans of European ancestry, the gene may remain active throughout life. This appears to be caused by a harmless recessive mutation affecting the mechanism that would normally shut the gene off. Adults of non-European ancestry are far more likely to develop lactose intolerance than adults of European descent. Fortunately for individuals who are lactose intolerant, there are over the counter enzyme tablets that can enable them to eat dairy products with gusto. In this Lab, you will perform an experiment using lactase tablets to explore enzyme function.

You will also be taking on the role of an enzyme in a Lab that simulates different conditions that might affect enzyme function in a cell. You will be testing the effects of a variety of conditions on “Toothpickase”, a fictional enzyme that breaks down toothpicks.

Tabletop Lab – Toothpickase and Lactase (Google Doc)

It is recommended that you print out the above Lab (linked) and record your data and answer the analysis questions by hand as you complete the Lab. This Lab is not to be turned in or graded. You will need to obtain the following supplies before you begin the Lab:

• 375 flat plain toothpicks

• 25 colored flat toothpicks, if you cannot find colored toothpicks, you can color them yourself using a marker.

• 1 large bowl of tap water

• Ice, enough to fill your large bowl with ice water mixture

• Stopwatch

• 1 small sauce pan, to boil a small amount of liquid on the stovetop or hot plate.

• 2 Lactase tablets such as Lactaid, easily found in your local grocery store or pharmacy

• Glucose tablets, easily found in in your local pharmacy, typically located near diabetic supplies.

• Glucose urine test strips, you may be able to find these at your local pharmacy, but many pharmacies don’t stock these anymore. You may have to order them online.

• 7 small cups, small juice cups or disposable Dixie cups would work well.

• Masking tape, to label your small cups.

• 1 and ½ teaspoon measuring spoons

• 6 stirring rods, toothpicks will work nicely.