Effects of pH on Lactase Enzyme

Today we started with the following daily questions which led to our first enzyme activity:

We then did a demonstration to show the activity of Lactase.

We started with the following supplies:


Milk, Powdered Lactase Enzyme, Microtubes, glucose test strips and Vinegar.

We first just wanted to see how lactase works so we added milk to a tube and tested for glucose

In this case the milk tested NEGATIVE for Glucose.  This is because the sugar found in milk is LACTOSE.  The Glucose and Galactose that make up glucose have not been separated yet.

Next up...... we added Lactase to the milk and tested again......

The test strip on the LEFT shows that when adding Lactase enzyme to the milk.
This time we DO see the presence of glucose.  This is because the enzyme lactase cuts the bond between galactose and glucose found in a lactose molecule.

Finally, we wanted to see the effects of pH on enzyme activity.  This time you added some Vinegar (an acid) to the lactase. 

Depending on the concentrations of acid, lactase, and milk.... you had a variety of results.  Some of yours ended up having MORE glucose in them, others the reaction didn't happen at all and some of you it worked less.

This was all indicated by different color changes on the test strips.
       What this tells us is that pH DEFINATELY effects how well the enzymes work!!

More tomorrow on enzyme activity.... this time we'll look at temperature.

GREAT JOB TODAY!!!!!