Laboratory Experiment Report: How Temperature Affects Lactase’s Action On Lactose

Abstract

Lactase, an enzyme, breaks down lactose into galactose together with glucose. This experiment was aimed at demonstrating lactase’s action on lactose. Besides, it was aimed at demonstrating how temperature affects the action.

Introduction

This experiment was aimed at demonstrating lactase’s action on lactose. Besides, it was aimed at demonstrating how temperature affects the action. Lactase, an enzyme, breaks down lactose into galactose together with glucose. Mammals require the enzyme to process lactose, which is commonly found in milk. As a mammal grows, it gradually loses its capacity to produce enough lactase and has to take in particular supplements. Lactase speeds up the breaking of the indigestible and insoluble lactose, a disaccharide, into soluble galactose together with glucose. Lactose speeds the breakdown by catalyzing the hydrolysis of lactose by reducing the quantity of the needed energy. The functioning of lactase, like any other enzyme, is optimal within a specific temperature range. Usually, the functioning of lactase is optimal at room temperature or slightly above it (Gaman & Sherrington, 1981). The experiment was founded on the hypothesis that the rate of the action of lactase on lactose increases with a rise in temperature.

Methods

The materials used in the experiment were:

  • Four cups of milk
  • A small container of apple juice
  • Lactaid
  • Reagent glucose analysis strips
  • Two 25 ml graduated cylinders
  • Ice
  • Hot pot
  • Test tubes and test tube racks
  • Thermometers

The procedure followed was:

  1. The class was divided into groups. Each of the groups was given four test tubes and two 25 ml graduated cylinders.
  2. Each of the teams determined the concentration of glucose in the provided standard glucose solution using reagent glucose analysis strips.
  • Each group poured milk into four test tubes and determined the concentration of glucose in the milk in each of the test tubes using reagent glucose analysis strips. The concentrations were noted down as “start glucose concentrations”.
  1. One of the test tubes was placed on ice, one was left at room temperature, one was heated in a warm water bath to about 37°C, and the last one was heated in the bath to about 100°
  2. Two drops of the lactase-containing lactaid were put into each of the test tubes. The concentration of glucose in the milk in each of the test tubes was determined using reagent glucose analysis strips. The concentrations were noted down as “end glucose concentrations”.
  3. The findings were recorded

Results

Temperature (°C)

Glucose Concentration (mgdL-1)

0 50
20 1000
37 2000
100 0

            The table above shows the results got in the experiment. As shown in the table above, the glucose concentration in the tubes increased gradually as temperature. Even then, the concentration dropped abruptly at a specific temperature. The concentration showed the rate of the action of lactase on lactose.

Figure 1 Glucose Concentration vs. Temperature

Figure 1: The graph above shows the results got in the experiment. As shown in the table above, the glucose concentration in the tubes increased gradually as temperature rose. Even then, the concentration dropped abruptly at about 40°C. The concentration showed the rate of the action of lactase on lactose.

Discussion

As noted earlier, lactase breaks down lactose into galactose together with glucose. Mammals require the enzyme to process lactose, which is commonly found in milk. As a mammal grows, it gradually loses its capacity to produce enough lactase and has to take in particular supplements. Lactase speeds up the breaking of the indigestible and insoluble lactose, a disaccharide, into soluble galactose together with glucose. Lactose speeds the breakdown by catalyzing the hydrolysis of lactose by reducing the quantity of the needed energy (Gaman & Sherrington, 1981).

The action of lactase on lactose is most optimal at a temperature of about 37°C. Temperatures that are below 37°C inhibit or slow down the functioning of the enzyme. Temperatures that are above 37°C as well inhibit or slow down the functioning of the enzyme. Notably, at very high temperatures, the functioning of the enzyme is affected by the denaturing of the enzyme. The enzyme is denatured by high amounts of heat since it is protein-based. When the enzyme is denatured, its molecules’ shape is lost. The shape of a protein molecule determines its functioning. That means that denatured lactase molecules lose are incapable of carrying out their functions as expected.

One can conclude that the activity of lactase increases with increasing temperature. This conclusion supports the hypothesis that the action of lactase on lactose increases with a rise in temperature. The method used in the laboratory experiment was effective in determining whether or not the action of lactase on lactose increases with a rise in temperature. The experiment’s outcomes could have been improved in terms of their accuracy by testing the concentration of glucose at a wider range of temperatures. Even then, the results got from the experiment were expected.


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