Download Building Monomers of Macromolecules

Building Monomers of Macromolecules
Marshmallow Lab
Introduction:
The term macromolecule by definition implies "large molecule". In the context
of biochemistry, the term may be applied to the four large molecules that make up
organisms --- nucleic acids, proteins, carbohydrates, and lipids. Macromolecules are
made of smaller subunits called monomers.
Materials:
3 nitrogen (green)
6 carbon (pink)
6 oxygen (orange)
12 hydrogen (yellow)
Toothpicks
Task:
Construct each of the following monomers and answer the questions. After
constructing each monomer, raise your hand to be checked to see if it correct.
REMEMBER: Molecules are 3-dimensional so models will not always be flat!
Background info: Living cells are made up of mostly water. The rest of the cell is largely made
up of compounds that contain Carbon. Living things are made up of proteins, DNA, fats, and
sugars. All of these molecules are made of Carbon. Carbon containing compounds are called
organic. Inorganic compounds do not contain carbon. Therefore, living things are composed of
organic compounds.
During this lab activity, you will be exploring the structure of these compounds. This will
involve making sketches and models. There will also be several questions that you must answer
on your answer sheet. For your drawings (sketches) you will need colored pencils to indicate the
elements involved:
Atoms join together to form molecules. These molecules are held together by bonds. In this lab
you will use toothpicks to represent the bonds. Important note: use one toothpick to represent a
single covalent bond, and two toothpicks to represent a double covalent bond. Remember,
covalent bonds are bonds in which electrons are shared.
KEY:
Single covalent bond
Double covalent bond
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Part I: Proteins
Proteins are made of subunits called amino acids and are used to build cells and do much of
the work inside organisms. They also act as enzymes helping to control metabolic reactions
in organisms. Amino acids contain two functional groups, the carboxyl group (-COOH) and
the amino group (-NH2). There are 20 amino acids, each characterized by their different
R, or remainder, groups.
Construct Glycine.
Place a BOX around the amino group on this picture.
Circle the carboxyl group on this picture.
1. The term “amino” refers to the group of atoms –NH2. Find each amino group and draw
a square around it. Label.
2. “COOH” is called a carboxyl group. Draw a circle around the carboxyl group. Label.
3. What are the monomers of proteins?
4. Name 3 things attached to the center carbon in ALL amino acids.
a.
b.
c.
5. How many amino acids exist? ________
6. What element is found in amino acids that isn't found in simple sugars like glucose
or fructose?
7. Amino acids join together to make what type of macromolecule?
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8. What are some of the functions of proteins in the body? (List several)
a.
b.
c.
H
H
H
O
N
C
N
O
C
O
C
H
H
H
H
C
C
H
O
H
H
H
H
ALANINE
GLYCINE
9. What is the difference between these two amino acids?
10. Now make these two amino acids with your marshmallows. Break a toothpick in
half and use both sticks to show the double bond.
11. We will now form a “dipeptide”. This molecule is made by combining the 2 amino
acids. The bond connecting the 2 amino acids is called a peptide bond.
What does the prefix “di” refer to in this molecule? _____________
Dipeptide
H
H
H
H
H
O
H
H
O
H
12. Connect your two marshmallow models as shown above.
13. What molecule was removed between the two amino acids?
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Part II: Carbohydrates
Carbohydrates are an organic molecule that is an important energy source for the body as
well as structural components for plants. We commonly refer to carbohydrates as sugars
and starches. Simple sugars are called monosaccharides.
Construct glucose or fructose with marshmallows.
H
Glucose
H
H
H
H
14. Look at the glucose molecule.
How many Carbon, Hydrogen, and Oxygen atoms are there?
C_____________
H______________
O_____________
15. Have you or your partner construct the glucose model.
The other partner will construct the fructose model.
16. What is the ratio of carbon to hydrogen to oxygen. See question #14. Reduce to
lowest common denominator.
 C_______: H _______: O _______
17. Simple sugars like glucose are called
_M
___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ _S_.
18. What is the primary function of carbohydrates for the body?
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19. Sucrose (table sugar), can be made by joining the glucose and fructose
molecules together. Glucose and fructose are both monosaccharides. (mono=one,
saccharide). What then, would be an appropriate name for Glucose since you are
combining 2 monosaccharides together? *Hint- use prefix!
_________________________________
20. Now combine the two by removing an OH from glucose and an H from fructose.
GLUCOSE
H
Bond the C
to the O
C
H
H
H
H
H
H
H2O
21. How is this process similar to joining amino acids to make a dipeptide?
22. Name three polysaccharides we have talked about.
a.
b.
c.
23. Copy the disaccharide below using the proper colors for each element.
Carbons are red, oxygens are orange, and hydrogens are yellow.
(Ex. see glucose and fructose below).
H
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Part III: Lipids
Lipids are large, nonpolar (won't dissolve in water) molecules. Lipids are basically fats, oils,
and waxes. Lipids have more carbon and hydrogen atoms than oxygen atoms. Fats are
made of a glycerol (alcohol) and three fatty acid chains. This subunit is called a
triglyceride.
Construct Glycerol.
Place a CIRCLE around a hydroxyl group. The hydroxyl group is OH.
*Remember
The C binds
to the
O here

24. Glycerol is one of two molecules that make up a monomer known as
_T_ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ _S_.
25. Besides glycerol, what other molecules make up a triglyceride?
26. Triglycerides are the monomers for what type of macromolecule?
27. Give 3 types of lipids.
a.
b.
c.
28. Construct the fatty acid below.
Place a BOX around the hydrocarbon (CH) chain on this picture.
Circle the carboxyl (COOH) group on this picture. Three of these tails together
forms the triglyceride, which is the subunit of lipids.
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Part IV: Nucleic acids
Nucleic acids carry the genetic information in a cell. DNA or deoxyribose nucleic acid
contains all the instructions for making every protein needed by a living thing. RNA copies
and transfers this genetic information so that proteins can be made. The subunits that
make up nucleic acids are called nucleotides.
Construct Cytosine.
30. Construct cytosine. Use a split toothpick to represent the double bond.
31. Cytosine is an example of a nitrogen base found on _______________ acids.
32. Name the 2 nucleic acids found in organisms.
33. Cytosine is a subunit of nucleic acids called what?
34. Draw the nitrogenous base Cytosine below, color code the elements of it, and
color the sugar backbone and the phosphate group. Make sure to color code it [Nbase colors (yes you have to color code cytosine) + Sugar- blue, Phosphate- Pink]
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