• Enzymes are proteins that catalyze chemical reactions.
  • protein = chain of amino acids
  • catalyze = speed up a chemical reaction
• Our bodies contain thousands of kinds of enzymes.
• Lactase is an enzyme. It catalyzes the breakdown of lactose, a sugar, into galactose and glucose, two other sugars.
• People whose bodies don't make enough lactase are lactose intolerant. The lactose in dairy products makes them feel sick. Lactaid, a drug that contains lactase, helps them digest lactose.

How does the milk treated with lactase taste compared to the plain milk?

What does the lactase taste like?

Did the lactase itself add the different flavor? What did the lactase do? Why did this change the flavor of the milk?

In addition to tasting the change that lactase produces in the milk, we can see the change by doing a Fehling's test for sugars.

• Lactase speeds up the breakdown of one large sugar molecule into two smaller sugar molecules.
• Each sugar molecule reacts with a blue copper atom in the Fehling's solution to turn the copper into to red-orange precipitate.

Will milk treated with lactase change the solution's color more than or less than untreated milk? (What's your hypothesis?)

Of all of the students who tested the milk, how many found a bigger color change with the lactase-treated milk? . . . the untreated milk?