Download Lactose Intolerance Lesson

LACTOSE
INTOLERANCE
Lactose intolerance is the inability to digest lactose, a
carbohydrate found in milk and other dairy products.
Lactose
To properly digest lactose, each lactose molecule must react
with one molecule of water. This reaction breaks the polymer
into two monomers, which can then be used for energy.
Lactose
O
H
H
Water
Most humans are able to catalyze the breakdown of lactose
using an enzyme called lactase.
O
H
H
Lactase
If lactose does not break apart, it cannot be used for energy.
It sits in the intestines and starts to ferment.
Fermentation of lactose in the gut, causing gas:
Lactose intolerant individuals do not produce the lactase
enzyme, or they produce it incorrectly.
Identify the reactants in this reaction.
Lactose and H2O
O
H
H
Lactase
Explain why the lactose and water will not react without the
help of an enzyme.
High A.E.
O
H
H
Lactase
Explain how the enzyme lactase catalyzes this reaction.
Lowers the A.E.
O
H
H
Lactase
Explain how the enzyme lactase lowers the A.E. of this
reaction.
Holds the reactants in place
Makes the reaction easier
O
H
H
Lactase
Explain why lactose-intolerant individuals could not use a
different enzyme to catalyze the breakdown of lactose.
The fit between enzyme and substrate must be precise
Lock and key
Explain why a person would have trouble digesting lactose
when they have a high fever.
Enzymes are proteins
Change shape at high temperatures