Name ______________________________
Carbohydrate Structure:
Monosaccharides and Polysaccharides
Part 1: Monosaccharides
 Examine your bag of beads.
 Your beads represent monosaccharides, or simple sugar molecules.
 Place your small plates labeled “Glucose,” “Galactose,” and “Fructose” in front of you. Place all
white beads into the Glucose plate, all orange beads into the Galactose plate, and all yellow beads into
the Fructose plate.
1. What is the difference between the three groups? ________________________________________
2. Except for this difference, are the beads similar? How? __________________________________
3. Each monosaccharide has a particular molecular structure. Examine the chart below and fill in the
blanks.
Name
Glucose = White Bead
Galactose = Orange Bead
Fructose = Yellow Bead
Molecular
Structure
# of Carbon
atoms
# of Hydrogen
atoms
# of Oxygen
atoms
Molecular
Formula
6
12
6
C6H12O6
4. Because of their similarities and differences, these structures are called structural isomers. What do
they have in common? What is different about them?
Part 2: Polysaccharides
A long polymer made of monosaccharides is called a polysaccharide. Cells connect many monosaccharides
together to store them, saving them for later energy usage. Cells also may string together monosaccharides
and use them as part of their cell walls. Different polysaccharides are formed when monosaccharides are
linked in different way.
A. Cellulose: Strong molecule used in plant cell walls
Take a long green pipe cleaner and fill it with white beads (which represent ____________________)
The bonds between the white beads are represented by the green pipe cleaner. These bonds are very
strong and are indigestible to most animals, including humans.
B. Starch: Sugar storage molecule used in plant cells
Fill a long white pipe cleaner with white beads (which represent ____________________________)
The bonds between the white beads are represented by the long white pipe cleaner. These bonds are
relatively weak and can be broken easily. Animals can break down (or digest) starch molecules into
small monosaccharides that animal cells can use for energy.
C. Glycogen: Sugar storage molecule used in animal cells
Fill a long red pipe cleaner with white beads (which represent
______________________________)
Also, fill another red pipe cleaner with white beads and connect the end of the one piece to the middle
of the long piece, creating a branched structure.
Animal cells store glycogen in liver and muscle cells, keeping the monosaccharides in the string for
later energy usage.
Review
1. A rabbit eats a carrot. A carrot is part of a root of a carrot plant and plants often store their extra
sugar in their roots. What polysaccharide is the rabbit eating? ______________________________
2. The rabbit has chemicals in its stomach that breaks down the polysaccharide. What reaction is used to
break down a polysaccharide (example of a polymer)? ___________________________________
3. After breaking down all of the plant polysaccharide into glucose molecules and using some to run away
from the neighborhood Chihuahua, the rabbit stores the rest of its sugar molecules in its own
polysaccharide.
a. What polysaccharide do the rabbit’s cells build? ____________________________
b. Where does the rabbit store this polysaccharide? ___________________________
c. Why is it important that the rabbit stores that polysaccharide and why does the location of
storage matter?
Name ______________________________
Lipid Structure:
Triglycerides and Phospholipids
Part 1: Triglycerides
A triglyceride is made of three fatty acids connected to a glycerol molecule.
Connect three of your fatty acid chains (medium length pipe cleaners) to a short green pipe cleaner, which
represents glycerol.
1. To build a triglyceride (a large molecule), what chemical reaction will take place? ________________
2. 3 fatty acids + 1 Glycerol  ___________________ + ____________________
3. Triglycerides are the main component of oils and fats. Would you expect triglycerides to be polar or
nonpolar? Explain.
Part 2: Phospholipids
There are other types of lipids besides the triglyceride. A phospholipid is made of a glycerol molecule
connected to two fatty acid molecules and a phosphate group.
Connect two fatty acid chains to a glycerol molecule. On the top third of the glycerol molecule connect a
short red pipe cleaner containing a large bead. This large bead represents a phosphate group.
1. Fatty acid chains, when by themselves, do not dissolve in water. Are
fatty acids hydrophobic or hydrophilic?
__________________________________
2. Phosphate groups, when by themselves, do dissolve in water. Are
phosphate groups hydrophobic or hydrophilic?
__________________________________
3. A simplified diagram of a phospholipid is shown on
the right. The “head” is a phosphate group and the
two “tails” are the fatty acid chains. Label which part
is hydrophobic and which part is hydrophilic.
4. Below is a diagram of the plasma membrane (cell membrane). The plasma membrane is made up of a
double layer of phospholipids, the tails sticking to tails and the heads sticking to heads within the same
layer. What parts of the plasma membrane (and phospholipids) are exposed to water? Which parts are
hidden from water?
Name ______________________________
Protein Structure:
Amino Acids and Polypeptides
Part 1: Amino Acids


Examine your bag of beads. Your beads represent amino acids.
Pour your beads onto a large plate.
1. How are your beads different? Describe the differences between three beads.
2. How are the beads similar?

Each type of amino acid has a particular structure. Look at the amino acid chart provided by your
teacher and answer the following questions.

On the right, there is a general structure
diagram of an amino acid.
3. What does each amino acid have in
common?
4. What makes different amino acids different?
5. How do you think “amino acid” got its name?
Part 2: Polypeptide
Two amino acids bonded together are called a dipeptide.
1. What is the reaction that takes place between two smaller biological
molecules to form one larger biological molecule? _________________
2. Finish the chemical equation for the reaction below:
Amino acid + Amino acid  ___________________ + ___________________
The bond between two amino acids in a chain is called a peptide bond.
A polymer chain of amino acids, strung together with covalent bonds, is called a polypeptide.
***Each person should fill a pipe cleaner with beads of different colors, shapes, and sizes. Make sure you use
the letter beads to form a short word (3-8 letters) long within your pipe cleaner polypeptide.
A. Sequence of Amino Acids
1. Describe the first 6 beads on your polypeptide. (Example: yellow heart, pink letter B, red round
bead…)
The sequence of your amino acids in your polypeptide is called the primary structure of your
polypeptide.
2. Is your polypeptide sequence different from your partners’? How?
Polypeptides are produced from “blueprint instructions” stored in the cell’s DNA. Each type of polypeptide is different,
just as different machines built from different instructions are different. The structure and function of a polypeptide is
determined by its sequence.
B. 3-Dimensional Structures

Bend your polypeptide to form a helix, like the one on the right. This is called a
secondary structure. Draw yours below:

Take your helical polypeptide and fold it into an even more complex folding shape.
Draw a rough picture below. This is called a tertiary structure.

Pick up two polypeptides your group built. Fold them over each other, twisting
them so they stay together. You have now formed a functional protein, which can
be described as having a quaternary structure. Sketch it below.
Review
1. Are the terms protein and polypeptide synonymous? Explain.
2. As you view your folded polypeptide, are all beads equally important to the structure or the message
you placed in your polypeptide? Explain your answer. How do you think this relates to real
polypeptide sequences and structures? Do you think all amino acids in a sequence are equally
important?