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Name: ____________________________________________
Date: ______________________
Per: ________
LAB: ENZYMES
In class, we have been discussing the four main macromolecules essential to living organisms. Collectively
known as biomolecules, carbohydrates, lipids, proteins, and nucleic acids are all organic compounds composed
primarily of carbon, hydrogen and oxygen.
Proteins play a significant role in the structure of our tissues and organs as well as in cellular metabolism.
Enzymes are proteins produced by the body that act as catalysts, speeding up the chemical reactions that are
constantly occurring within our bodies. Enzymes can catalyze reactions that break things down, which are called
catabolic reactions. They can also catalyze reactions that put things together, which are called anabolic reactions.
Enzymes are very specific to what reactions they catalyze. This is because of the way in which the substrate
molecule (the molecule(s) the enzyme acts upon) binds to the active site. The active site is a small space on the
enzyme where the substrate molecule attaches. In order for the enzyme to catalyze a reaction, the substrate must fit
into the active site like a jigsaw puzzle piece. In other words, the chemicals that are going to react have to fit into
that special place on the enzyme where they will bind. If the substrate does not fit, that enzyme will not catalyze the
reaction.
In this lab, you will investigate the actions of various enzymes as well as models representing the structure
and function of enzymes. This lab consists of six lab stations through which you and your group will rotate. At
each station, you need to perform the assigned tasks, make observations, think critically about the information you
gather, and answer the questions.
Station 1: Milk and the Lactase Enzyme
Dairy products such as milk contain a sugar called lactose. Lactose is a disaccharide (meaning “two sugars”) that is
composed of the two simple sugars Glucose and Galactose. Some people are “lactose intolerant,” meaning that
their digestive system cannot break down the Lactose sugar into these simpler sugar molecules (they do not make
the proper enzyme). In order to avoid the stomachaches that result from dairy products that aren’t broken down in
digestion, lactose intolerant people can take pills such as Lactaid or Dairy Ease along with any dairy they consume.
These pills contain an enzyme called lactase that breaks down the lactose for them.
At this station you will find two types of milk. The Publix 2% is regular milk and the Lactaid is regular milk with
the enzyme lactase added. Using the small cups provided, try both varieties of milk. Please use just one cup per
person. Throw the cups in the trash after you’ve used them.
B. Does the Lactaid milk taste different than the regular milk? If so, how is it different?
C. What has happened to the Lactose sugar in the Lactaid milk because of the addition of the
enzyme lactase?
D. Is the glucose level higher in the regular milk or the Lactaid milk? Explain your reasoning.
Station 2: Gelatin (Jell-O) and Pineapple
You have probably eaten Jell-O before, and maybe you’ve even made it yourself. Jell-O is a flavored gelatin, which
is a type of protein. Sometimes, people put fruit in Jell-O like grapes or strawberries. If you have ever read the box,
you may have noticed the directions tell you not to add fresh pineapple or kiwi. Why might this be?
At this station, you will examine how Jell-O gelatin is affected by fresh pineapple. There are 4 dishes: the first is
your control containing just normal Jell-O, the second contains Jell-O and canned pineapple, the third contains
Jell-O and fresh pineapple, and the fourth contains Jell-O and meat tenderizer (a catabolic enzyme). Make
observations about these dishes, and answer the questions below.
A. In which samples does the Jell-O look unchanged (normal)?
B. In which samples does the Jell-O look as though it has been affected by what we’ve put in them?
(Hint: it will appear runny)
C. Since this entire lab is about ENZYMES, what can you hypothesize about the samples that seem
to be “breaking down” the Jell-O? Be specific!
(Hint: Jell-O is made of what type of biomolecule?)
D. Canning companies have told us that pineapple must be cooked at very high temperatures
because of its dense flesh. Knowing this, how do you think heat affects the function of enzymes?
(Hint: Did the canned pineapple that had been heated have any affect on the Jell-O?)
E. If you were having a barbeque, would it make sense to try to use pineapple as a meat tenderizer?
Why or why not? (Think about the science, not the taste!)
Station 3: Lock and Key Model
This station is a model, or representation, of enzyme structure and function. Before you are a lock and a ring of
keys. As you surely know, only one specific key will work to open a lock. Other keys may slide into the lock, but
will not open it, while some keys may not fit into the lock at all. Try the keys and see which one, if any, opens the
padlock.
Go back and read through the introduction to this lab carefully. Make sure you understand how enzymes work and
what conditions are needed for proper functioning of an enzyme. Then answer the questions below.
A. In this enzyme model, what do you think the lock represents (enzyme, active site or substrate)?
Explain WHY?
B. What do you think the keys represent (enzyme, active site or substrate)? Explain WHY?
C. Scientists often use the “lock and key” example to explain enzyme function. If you were teaching
someone bout enzymes, how would you explain the concept using this model and the following key
words: substrate, active site, enzyme, lock, key, & keyhole.
Station 4: Enzyme Perfection
This station is another model used to help you understand enzymes and, more specifically, how substrates bind to
enzymes. The game before you, Perfection, is one you may recognize. Each small square on the blue board
represents an enzyme, with the empty shape on each square representing the active site. The yellow game pieces
are differently shaped and represent the substrate molecules that must find the proper active site in order to be
catalyzed! Fit the substrates on the appropriate enzymes, and then answer the questions below.
A. Describe what you had to do to place all the “substrates” into the proper “active sites”?
B. When you found a substrate that fit an active site, did it have to be positioned in a certain way in
order to fit, or could you fit it in any orientation (sideways, upside down, right side up, etc)?
C. Use this model to explain the relationship between substrates and enzymes and how they bind
together at the active site.
Station 5: Crisco and Noodles and Jell-O, Oh My!!!
At this station, you will find 6 dishes containing three different types of food products. Three containers will be
untreated and will serve as controls. The other three containers have been coated with meat tenderizer. Each dish is
labeled with the food it contains and if it has been covered with meat tenderizer or not. The food samples include
noodles (carbohydrate), Crisco (lipid), and Jell-O (protein). Look at each food sample and observe whether or not
the meat tenderizer has significantly changed the structure and appearance of the food from how it normally looks.
A. Which one of the foods was affected by the meat tenderizer?
B. Which of the foods appears unaffected/unchanged by the meat tenderizer?
C. The word “enzyme” refers to a protein that speeds up chemical reactions. The word “specificity”
can be defined as being “picky” or “choosy.” Explain in your own words how this station shows
enzyme specificity. (Hint: What type of biomolecule was affected by the enzyme in the meat
tenderizer?)
Station 6: Anabolism and Catabolism with Lego’s
When you read the introduction to this lab, did you catch the part about enzymes acting on both reactions that put
things together (anabolic reactions) and reactions that break things down (catabolic reactions)? To explain a little
more, anabolism combines simple molecules to form more complex molecules, while catabolism breaks down
complex molecules in order to yield energy (from the breaking of atomic bonds) and to create simpler molecules
(like in digestion).
The Lego’s at this station represent the building blocks of a nutrient. Have one person in your group put all the
Lego’s together. Have another person in your group take this Lego creation apart. Think about what is happening
and answer the questions on the back of this page.
A. Was the person who put the Lego’s together performing anabolism or catabolism? Explain why
you think so.
B. Was the person who took the Lego’s apart performing anabolism or catabolism? Explain why
you think so.
C. Listed below are some enzyme-driven reactions. For each one, decide if the process is
ANABOLIC or CATABOLIC and write your answer below the statement.
a. The liver stores the monosaccharide glucose as a bigger molecule called glycogen.
b. You eat a bagel and the starch polysaccharide is broken down into smaller disaccharide
and monosaccharide molecules.
c. In the process of cellular respiration, glucose is broken down to yield energy in the form
of ATP.
d. Inside the cells of your body, an organelle called the ribosome packages amino acids
together in the form of proteins.
D. Based on what you now know about anabolic and catabolic reactions, explain why the illegal
performance-enhancing drugs that some athletes use are called “anabolic” steroids?