Activity 2.2.3: The Biochemistry of Food
Introduction
The foods we eat contain the nutrients and molecules we need to survive. Some of
these molecules are used to build our body parts, some are used to drive chemical
reactions necessary for life, and others are used as sources of energy. Many of the
molecules in our bodies are very large and are made by combining smaller
molecules. These very large molecules are called macromolecules.
In this activity you will take a much closer look at the structure of some of the
molecules listed on the food labels you observed in the previous activity and begin to
develop an understanding of their functions in your body. You will complete a series
of puzzles to explore the biochemistry of food. You will begin to see how the body
works to harness the power of what we eat through the assembly and disassembly
of macromolecules.
Procedure
Part I: Chemistry Basics
1. Open the interactive presentation Chemistry of Life. Note that you will be
working through this presentation in bits and pieces as you complete this activity.
The presentation will prompt you to return to this activity document when
appropriate.
2. Complete Part I: Chemistry Basics of the interactive presentation. Take notes in
your laboratory journal so you can refer to them later. Be sure to pay close
attention to the information on chemical bonds. These notes go on panel 3 of
your portfolio.
Part II: Molecular Puzzles
3. Go up front and get a set of puzzle pieces. You can get ANY set at all to start
with. Finish this section and then jump in the instructions to that set.
4. Take out the red oxygen pieces and the white hydrogen pieces. Figure out how
they fit together. You should notice that there’s only ONE WAY to put the pieces
together. How many oxygen atoms are there? Hydrogens? What molecule
have you made? You should have figured out that it’s WATER (H2O). The
reason you build this molecule first is that water is FOUNDATIONAL in life and
will have a MAJOR role in forming and breaking apart the molecules we need to
survive, so you’d better know what a molecule of water looks like.
5. Check that your panels are set up correctly. Panel 4 should look like this:
© 2013 Project Lead The Way, Inc.
PBS Activity 2.2.3 The Biochemistry of Food – Page 1
with the panels each being half a sheet of paper (hamburger style). Please do
NOT add pictures until you come to that place in the directions! I want you to
build understanding as you make the models and USE THAT to determine which
pictures to add.
6. Here is what panel 5 should look like:
And if you flip open the shutter fold, you should see the table inside of it, like this:
© 2013 Project Lead The Way, Inc.
PBS Activity 2.2.3 The Biochemistry of Food – Page 2
DO NOT ADD PICTURES until you’re told to. You’ll add pics as you work
through the puzzle—it will be part of how you build understanding!
7. Ok, you’ve finished the basics. There are four basic rules for building all
models. You’ll need to reference these CONSTANTLY, so I’ve printed copies. If
you don’t already have a copy, see me for one. Adding them to your portfolio is
optional. The rules are:

Oxygen and Hydrogen atoms can bond with anything they fit with.
Remember that each snap represents a covalent bond.

A molecule is stable (complete) only if it has no available pegs or slots
(Note: proteins are an exception).

Macromolecules are assembled by connecting puzzle pieces of the SAME
color and oxygen and hydrogen atoms.

The lettering on the puzzle pieces must be visible and all in the same
general direction when assembling the puzzle pieces.
8. Congratulations! You’re now ready to build macromolecules. Jump in the
directions to whichever kind of puzzle pieces you have. The order that you start
working with the pieces DOES NOT MATTER.
Puzzle Set #1 – Carbohydrates
9. So as not to confuse you, I’ve cut/pasted what you need from the PowerPoint so
that you don’t have to toggle back and forth. Here are the slides about carbs.
Read through them, adding info to your portfolio as you work:
Write down the FUNCTION of carbs, based on this slide. You really only need 12 words. Gives Energy
© 2013 Project Lead The Way, Inc.
PBS Activity 2.2.3 The Biochemistry of Food – Page 3
Write down the elements that carbs are composed of. Also, write down the
BUILDING BLOCK of carbs (monosaccharides). Determine what that means
(based on the roots mono and sacchar) and add that to your table.
The elements that are in carbs are carbon, hydrogen, and oxygen. The
building blocks would be the simple sugars like monosaccharides and
polysaccharides. Mono means one and saccharide means sugar so
monosaccharide means one sugar.
© 2013 Project Lead The Way, Inc.
PBS Activity 2.2.3 The Biochemistry of Food – Page 4
10. Note that in your kit, monosaccharides are the green pieces. Take out a
monosaccharide base piece (shown below) and some hydrogen and oxygen
atoms.
11. Use the rules described in step 12 to assemble your monosaccharide. Make sure
your completed molecule is visible on your desk. Get your completed
monosaccharide checked for a lab grade.
12. Find the PICTURE of a monosaccharide molecule that I gave you in your picture
packet. Now you know that a monosaccharide is a CARBOHYDRATE. Glue the
monosaccharide under the flap and label it monosaccharide.
13. Glucose, fructose and galactose are all monosaccarides. Make a note of that
under the picture or in the “examples” section of the table.
14. Build a second complete monosaccharide, identical in every way to the first one.
15. Put all other pieces back in the bag, so that all that is left out are your two
identical monosaccharides. This is very important so that you don’t get
confused!
16. Work with your teammate to decide how you can link the two monosaccharides
to make a disaccharide. Hint, you’ll have to break certain bonds and form new
bonds. The pieces that you remove and leave off the green rings should then fit
together into a very familiar molecule. Put that molecule together so that you
have a disaccharide and that molecule. Call me over and show me your
dissacharide and explain what byproduct molecule formed when you made your
disaccharide.
17. Here’s the PLTW slide about disaccharides:
© 2013 Project Lead The Way, Inc.
PBS Activity 2.2.3 The Biochemistry of Food – Page 5
18. Find the picture of the disaccharide from your picture packet. Glue it under the
carbohydrate flap. Record examples of disaccharides under the picture or in the
table, under examples. Also, add information about the literal meaning of
disaccharide (what’s di mean?). Di means two or double and saccharide
means sugar so disaccharide means two or double sugar. Some examples
of disaccharides are sucrose, fructose, and maltose.
19. fvvfv type of reaction is referred to as dehydration synthesis. Based on the action
you took to complete the puzzles, come up with a definition for the term
dehydration synthesis. The definition goes on page 4 in your portfolio. USE
WORD ROOTS to explain the process. The roots you’ll use are de-, hydr-, -tion,
syn- and –sis. Find a picture showing the process of dehydration synthesis that I
gave you and add it to panel 4 (along with your picture). Explain thoroughly what
happens, using complete sentences Dehydration synthesis is to take out
water and to bond together because we all syn together!! When you use
dehydration synthesis you take out a water molecule and bond together
two different molecuels.
20. Reverse the process you just completed to break down the disaccharide into two
monosaccharides. Note that your by-product water molecule was required in
order to re-create the original two molecules.
21. This type of reaction is referred to as a hydrolysis reaction. Based on the action
you took to complete the puzzles, provide a definition for this term on panel 4 of
your portfolio. Use the roots hydr-, lys, and sis to help explain it IN COMPLETE
SENTENCES. Add a picture showing the process.
Hydrolysis means to cut or split with water essientialy what happens is
instead of taking out a water molecule like you would in dehydration
synthesis you would actually use the water molecule to split a bond and
then add in the water molecule.
© 2013 Project Lead The Way, Inc.
PBS Activity 2.2.3 The Biochemistry of Food – Page 6
22. Think about which process—dehydration synthesis or hydrolysis—takes place in
your digestive tract. Add a picture of your digestive tract under that term and add
info about that to your definition.
23. Think about which process—dehydration synthesis or hydrolysis—takes place in
living things as they grow. Add a picture of a garden growing under that term
and add info about that to your definition.
24. Combine 3 to 4 monosaccharides to make a polysaccharide. Together with your
partner, discuss answers to the following questions:
a. What process did you use to make the polysaccharide—dehydration
synthesis or hydrolysis? Explain. We did Dehydration synthesis
because we took out a water molecule
b. Where would this polysaccharide-formation process occur? This
polysaccharide would occure when three Monosaccharides are
linked together.
Here are the PLTW slides on polysaccharides:
© 2013 Project Lead The Way, Inc.
PBS Activity 2.2.3 The Biochemistry of Food – Page 7
25. Place a picture of a polysaccharide under the carbs flap of your portfolio. Record
its literal meaning, using roots.
26. Make a note of examples under the picture of the polysaccharide or in the
“examples” section of your table.
27. Reverse the process you just completed to break down your macromolecule and
retrieve your monosaccharide. Together with your partner, discuss answers to
the following questions:
a. What process did you use to make the polysaccharide—dehydration
synthesis or hydrolysis? Explain. Hydrolysis would be the process
because water would break the bond and the water molecule was
added
b. Where would this polysaccharide-formation process occur? When
animals take in food the glucose molucuels link upp and that’s where
this process occurs.
28. Before moving to another puzzle set, make sure the carbohydrates section of
your table is COMPLETE. (It should be, if you’ve been following directions!).
You may now move to proteins or lipids. If neither is available OR you’ve done
both, move to the “wrap-up” section.
Puzzle Set #2 – Proteins
29. Get the proteins puzzle set.
30. Here’s a PLTW slide about proteins:
© 2013 Project Lead The Way, Inc.
PBS Activity 2.2.3 The Biochemistry of Food – Page 8
31. Write the function of proteins in 5 words or less in your table—KEEP IT SIMPLE.
32. State the building blocks of proteins in your table.
33. Obtain an amino acid base piece (shown below—they may vary, so just pick any
on that looks roughly like this) and some hydrogen and oxygen pieces. Note
which elements are present and record it in your table.
© 2013 Project Lead The Way, Inc.
PBS Activity 2.2.3 The Biochemistry of Food – Page 9
34. Follow the rules you learned to assemble the puzzle pieces and build an amino
acid as best you can’t (you won’t be able to with just these pieces…). Note any
problems with your puzzle.
35. You should have noticed that the red oxygen pieces and white hydrogen pieces
won’t fit on the top notch. Locate the additional blue piece called a variable
group, or R group. Note that there are 4 different variable groups in the kit even
though there are 20 variable groups that exist in nature. Add this piece to your
puzzle—pick any of them. Now it’s time to see Mrs. H and get credit for this
build.
36. Take a moment to look at the Chem4Kids website
http://www.chem4kids.com/files/aminoacids/index.html and learn about the
structure of amino acids and the 20 different kinds.
37. Build another amino acid (make sure that it follows all the rules) and place them
side by side. Note that amino acids are the building block of proteins. Gee, that
sounds like it should go into your table! Now’s a good time to look at which
elements are in proteins and record that under “composed of.”
38. PUT AWAY all other puzzle pieces so that you don’t get confused!
39. Figure out which pieces you have to remove to combine the two amino acids to
make a dipeptide, a molecule of two amino acids. If you remove pieces,
remember to link them following the four basic rules. Here’s a PLTW slide that
will help you understand why this is called a dipeptide.
© 2013 Project Lead The Way, Inc.
PBS Activity 2.2.3 The Biochemistry of Food – Page 10
40. Work with your teammate to decide how you can link the two amino acids to
make a dipeptide (double amino acid). Hint, you’ll have to break certain bonds
and form new bonds. The pieces that you remove and leave off the blue pieces
should then fit together into a very familiar molecule. Put that molecule
together so that you have a dipeptide and that molecule. Call me over and show
me your dipeptide and explain what byproduct molecule formed when you made
your dipeptide.
41. Find the picture of the protein made of amino acids from your picture packet.
Glue it under the protein flap. Record examples of proteins under the picture or
in the table, under examples.
42. Note that this type of reaction is referred to as dehydration synthesis. Based on
the action you took to complete the puzzles, come up with a definition for the
term dehydration synthesis. The definition goes on page 4 in your portfolio. USE
WORD ROOTS to explain the process. The roots you’ll use are de-, hydr-, -tion,
syn- and –sis. Find a picture showing the process of dehydration synthesis that I
gave you and add it to panel 4 (along with your picture). Explain thoroughly what
happens, using complete sentences.
43. Reverse the process you just completed to break down the dipeptide back into
two amino acids. Note that your by-product water molecule was required in
order to re-create the original two molecules.
44. This type of reaction is referred to as a hydrolysis reaction. Based on the action
you took to complete the puzzles, provide a definition for this term on panel 4 of
your portfolio. Use the roots hydr-, lys, and sis to help explain it IN COMPLETE
SENTENCES. Add a picture showing the process.
45. Think about which process—dehydration synthesis or hydrolysis—takes place in
your digestive tract. Add a picture of your digestive tract under that term and add
info about that to your definition.
© 2013 Project Lead The Way, Inc.
PBS Activity 2.2.3 The Biochemistry of Food – Page 11
46. Think about which process—dehydration synthesis or hydrolysis—takes place in
living things as they grow. Add a picture of a garden growing under that term
and add info about that to your definition.
47. Combine 3 to 4 amino acids to begin a protein chain. Please note that actual
proteins can be THOUSANDS of amino acids long and fold in CRAZY
complicated ways, making proteins by far the most COMPLEX of any kind of
macromolecule! Together with your partner, discuss answers to the following
questions:
a. What process did you use to make the polysaccharide—dehydration
synthesis or hydrolysis? Explain.
b. Where would this polysaccharide-formation process occur?
Here’s a slide showing what structure proteins take on. Sketch the structure of a
protein—messy and knotted, like a ball of yarn, next to the picture I gave you.
48. Before moving to another puzzle set, make sure the proteins section of your table
is COMPLETE. (It should be, if you’ve been following directions!). You may now
move to carbohydrates or lipids. If neither is available OR you’ve done both,
move to the “wrap-up” section.
Puzzle Set #3 – Lipids
49. Here’s a PLTW slide about lipids:
© 2013 Project Lead The Way, Inc.
PBS Activity 2.2.3 The Biochemistry of Food – Page 12
50. Record the elements lipids are comprised of and the building blocks in your table.
51. Here’s another slide. Use it to record the function of lipids in 10 words or less:
52. Obtain the two pieces that make up a glycerol molecule (shown below) as well as
some hydrogen and oxygen pieces.
© 2013 Project Lead The Way, Inc.
PBS Activity 2.2.3 The Biochemistry of Food – Page 13
53. Assemble your pieces according to the rules 12 to form a completed glycerol
molecule. Remember, there should be no open spots!
54. Obtain one fatty acid chain piece (shown below) and additional hydrogen and
oxygen molecules. Note that this type of chain is referred to as a saturated fatty
acid. That is because there are no double bonds in the carbon chain. Find the
picture showing a saturated and unsaturated fatty acid and glue it under the lipids
flap.
55. Assemble your pieces to form a completed fatty acid chain. Remember, there
should be no open spots!
56. Work with your teammate to decide how you can link the glycerol to the fatty acid
chain. Hint, you’ll have to break certain bonds and form new bonds. The pieces
that you remove and leave off the yellow pieces should then fit together into a
very familiar molecule. Put that molecule together and set it aside.
57. Repeat this process with 2 more fatty acid chains, forming a triglyceride and 3
byproduct molecules. Call me over to see your work.
58. Note that this type of reaction is referred to as dehydration synthesis. Based on
the action you took to complete the puzzles, come up with a definition for the
term dehydration synthesis. The definition goes on page 4 in your portfolio. USE
WORD ROOTS to explain the process. The roots you’ll use are de-, hydr-, -tion,
syn- and –sis. Find a picture showing the process of dehydration synthesis that I
gave you and add it to panel 4 (along with your picture). Explain thoroughly what
happens, using complete sentences.
59. Reverse the process you just completed to break down the triglyceride back into
a glycerol and 3 fatty acid chains. Note that your by-product water molecules
were required in order to re-create the original four molecules.
60. This type of reaction is referred to as a hydrolysis reaction. Based on the action
you took to complete the puzzles, provide a definition for this term on panel 4 of
© 2013 Project Lead The Way, Inc.
PBS Activity 2.2.3 The Biochemistry of Food – Page 14
your portfolio. Use the roots hydr-, lys, and sis to help explain it IN COMPLETE
SENTENCES. Add a picture showing the process.
61. Think about which process—dehydration synthesis or hydrolysis—takes place in
your digestive tract. Add a picture of your digestive tract under that term and add
info about that to your definition.
62. Think about which process—dehydration synthesis or hydrolysis—takes place in
living things as they grow. Add a picture of a garden growing under that term
and add info about that to your definition.
63. Re-build the triglyceride, this time making it UNSATURATED. You’ll need to use
an unsaturated fatty acid chain, like the one shown below, in place of one of the
saturated chains. Have me check it when you’re done.
64. On the picture of fats under your flap, highlight the double bond on the
unsaturated fatty acid chain and explain that a double bond in the chain makes
the fat “unsaturated.” Discuss with your partner:
a. What are saturated fats saturated WITH?
b. Why are unsaturated fats called “unsaturated”?
65. Here are some examples of lipids. Note that double bonds are illustrated with a
double line and that the fatty acid chains are not labeled with elements. Every
zig is a carbon and they are always coated in hydrogen.
© 2013 Project Lead The Way, Inc.
PBS Activity 2.2.3 The Biochemistry of Food – Page 15
66. Before moving to another puzzle set, make sure the lipids section of your table is
COMPLETE. (It should be, if you’ve been following directions!). You may now
move to carbohydrates or proteins. If neither is available OR you’ve done both,
move to the “wrap-up” section.
Wrap-Up
1. Use this PLTW slide to complete the nucleic acids section of your table:
2. Note that you will not be using the molecular puzzles to work with nucleic acids,
as you already built DNA in Unit 1. You have a picture showing nucleic acids.
Place it under the nucleic acids flap.
© 2013 Project Lead The Way, Inc.
PBS Activity 2.2.3 The Biochemistry of Food – Page 16
3. Refer to the Anna Garcia Food Diary below and the results of your food testing
experiment to determine food examples FROM HER DIET that contain
carbohydrates, lipids, and proteins. This goes in the final column of your table.
Add these foods to the final column in your Student Response Sheet. Make sure
you have at least 3 GOOD examples (meaning it has a lot of that
macromolecule) for each of the 3 kinds of macromolecules.
Saturday – August 11, 2012
 Breakfast
o 2 egg whites, scrambled, no butter
o 2 slices thick turkey bacon
o 1 slice whole wheat toast with 1 pat butter
o 1 cup coffee with artificial sweetener and 1 tbsp. light coffee creamer
 Lunch
o 1 12oz can Sprite
o 1 turkey sandwich (2 slices whole wheat bread, 3 slices turkey lunch
meat, 1 slice cheddar cheese, ½ tbsp. mayonnaise)
o 16 fat-free tortilla chips with salsa
 Snack
o 1/4 cup dry roasted peanuts
o 1 small apple
 Dinner
o ½ cup apple juice
o 6 ounces salmon filet
o 1 cup brown rice cooked with salt and butter
o 1 cup steamed broccoli
 Dessert
o ½ cup sugar free lemon gelatin
Sunday – August 12, 2012
 Breakfast
o 1 cup Cheerios
o ½ cup skim milk
o ½ cup blueberries
 Lunch
o 1 cup low-fat strawberry yogurt
o 6 Ritz crackers
o 1 cup canned, low-sodium vegetable soup
o 1 12oz can cola
 Snack
o 1 single serving bag potato chips
 Dinner
o 2 slices thick crust pepperoni pizza (14” pizza)
o 2 cups tossed salad
o 4 tbsp. Caesar dressing
 Dessert
o 1 cup vanilla ice cream with ½ cup mini marshmallows
o 5 Oreo cookies
© 2013 Project Lead The Way, Inc.
PBS Activity 2.2.3 The Biochemistry of Food – Page 17
Monday – August 13, 2012
 Breakfast
o 1 cup whole milk
4. Here’s a PLTW slide on monomers and polymers:
5. Find the picture of monomers and polymers. Glue it down on panel 5. Explain
the difference between a monomer and a polymer. Use word roots (mono, poly
and mer). Relate monomers and polymers to dehydration synthesis and
hydrolysis. How do monomers become polymers? How do polymers become
monomers? Are the foods we eat mostly monomers or polymers? Write in
COMPLETE SENTENCES.
6. Find the picture showing ATP and the energy released as it is hydrolyzed. Glue
it down on panel 5. Explain how energy relates to food. How do we release the
energy from our food? Say where the energy is stored and how it is released.
Name the PROCESS by which it is released (is that hydrolysis or dehydration
synthesis). Use the terms polymers and monomers in your explanation. Explain
that energy in the body is stored as ATP (you have a picture illustrating it—add
that to your portfolio). Write in COMPLETE SENTENCES.
CONGRATULATIONS! YOU ARE
FINISHED WITH PANELS 4 AND
5—THAT WAS A LOT OF WORK
© 2013 Project Lead The Way, Inc.
PBS Activity 2.2.3 The Biochemistry of Food – Page 18