Vernier Software and Technology
Vernier Software & Technology

Lactase Action

Figure from experiment 18A from Agricultural Science with Vernier

Introduction

Lactose, a disaccharide sugar found naturally in mammalian milk, is utilized by infants as one of their initial sources of energy. During infancy, mother’s milk is often the child’s sole source of nutrition. This milk sugar, lactose, must undergo an enzymatic reaction that separates the disaccharide molecule into two monosaccharides; glucose and galactose. This action is carried out in the cells lining the small intestine. The enzyme facilitating the ‘breakage’ reaction is called lactase. After the split, the resulting simple sugar molecules are released and the lactase enzyme is available to react again. Glucose molecules are absorbed and transported to the liver while galactose molecules undergo another enzymatic reaction converting them to glucose.

In this lab, you will assess the functioning of lactase. One way is to determine if the enzyme is converting the disaccharide into glucose and galactose by measuring the amount of glucose produced. You can use glucose test strips, originally made for diabetics to detect glucose levels. The test strip turns a range of colors to indicate the sugar’s concentration in solution.

An alternative test for lactase activity measures the production of CO2 gas by yeast. Presumably, yeast are unable digest lactose. Yeast metabolize glucose aerobically during respiration, according to the equation:

{{\text{C}}_{\text{6}}}{{\text{H}}_{{\text{12}}}}{{\text{O}}_{\text{6}}}{\text{  +  6 }}{{\text{O}}_{\text{2}}} \to {\text{6 C}}{{\text{O}}_{\text{2}}}{\text{  +  6 }}{{\text{H}}_{\text{2}}}{\text{O  +  energy}}

water is produced and CO2 is released as the sugar is broken down in glycolysis. By monitoring the production of CO2, we can use yeast to indicate lactase activity.

Objectives

In this experiment, you will

  • Test the action of lactase.
  • Use glucose test paper to monitor the presence of glucose.
  • Determine if yeast can metabolize glucose, lactose, or galactose.

Sensors and Equipment

This experiment features the following Vernier sensors and equipment.

Option 1

Option 2

Additional Requirements

You may also need an interface and software for data collection. What do I need for data collection?

Standards Correlations

See all standards correlations for Agricultural Science with Vernier »

Agricultural Science with Vernier

See other experiments from the lab book.

1Introduction to Data Collection
2Acids and Bases
3Diffusion through Membranes
4Conducting Solutions
5Osmosis
6Respiration of Sugars by Yeast
7Reflection and Absorption of Light
8Soil pH
9Soil Salinity
10Soil Temperature
11Soil Moisture
12APhotosynthesis and Respiration (CO2)
12BPhotosynthesis and Respiration (O2)
12CPhotosynthesis and Respiration (CO2 and O2)
13Transpiration
14ACell Respiration (CO2)
14BCell Respiration (O2)
14CCell Respiration (CO2 and O2)
15The Greenhouse Effect
16Energy in Food
17AEnzyme Action: Testing Catalase Activity
17BEnzyme Action: Testing Catalase Activity
18ALactase Action
18BLactase Action
19Oxygen Gas and Human Respiration
20Biochemical Oxygen Demand
21Animal Temperature
22Lemon "Juice"
23Ohm's Law
24Energy Content of Fuels
25Photovoltaic Cells
26Wind Power
27Watershed Testing
28Interdependence of Plants and Animals
29Biodiversity and Ecosystems

Experiment 18A from Agricultural Science with Vernier Lab Book

<em>Agricultural Science with Vernier</em> book cover

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