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Carbohydrate, Proteins and Fat Lab
Scientists use a combination of biology and chemistry to understand life processes so therefore an
understanding of some chemistry of living things is necessary.
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CARBOHYDRATES
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Carbohydrates make up a large group of compounds found in cells.
Carbohydrates are used for energy as well as to make cell structures.
There are three different groups of carbohydrates – monosaccharides, disaccharides and
polysaccharides. Saccharide means sugar.
Monosaccharides
 A single sugar molecule is called a monosaccharide. Mono means one.
 Monosaccharides have different shapes because the atoms are arranged differently.
 Three monosaccharides are glucose, fructose, and galactose.
 Examine the structural formulas of these three sugars and answer the following questions.
Glucose
Galactose
1. What three elements are present in the three monosaccharides shown? (1 mark)
2. How many atoms of C are present in a molecule of: (1 mark each)
a. Glucose
b. Fructose
c. Galactose
3. Add subscripts to the following to indicate the proper chemical formula. Subscripts are
determined by counting the total number of carbon, hydrogen, and oxygen atoms in each
molecule.
(1 mark each)
a. Glucose: C H O
b. Fructose:
C H O
c. Galactose: C H O
Source: Kaskel, A. (1989). Laboratory biology: Investigating living systems (Teacher Annotated Edition). Merrill, WI:
Merrill Publishing Co.
This copy was made for a fair dealing purpose. Any further distribution must follow the Saskatchewan Polytechnic fair
dealing guidelines.
2
Disaccharides
 Are two monosaccharides joined chemically together. The prefix di means two.
 By chemically joining a glucose molecule with a fructose molecule, a double sugar called
sucrose is produced.
1. When glucose and fructose join, an OH is removed from one molecule and an H is removed
from another. Write the chemical formula for sucrose by adding together the chemical
formulas for glucose and fructose and then subtracting water.
(1 mark)
2. Different disaccharide molecules can be made by joining other monosaccharides in different
combinations. By chemically joining a glucose molecule with another glucose molecule a
maltose molecule is formed. Using the same method as question 1, write the chemical
formula for maltose.
(1 mark)
3. How does the formula of sucrose compare to maltose?
(1 mark)
Polysaccharides
 Polysaccharides consist of three or more monosaccharides chemically joined. The prefix
poly means many.
 Starch, glycogen and cellulose are the three most common polysaccharides in biology. They
consist of long chains of glucose molecules joined.
 The simple formula for a polysaccharide is written as (C6H12O6)n. The n equals the number of
times the C6H12O6 group is repeated.
1. Benedict’s Test
Materials
 Test tubes
 Test tube rack
 Test tube holder
 Grease pencil
 Benedict`s solution
 Droppers or Pipettes
 Hot Plate
 Water
 Beaker
 Monosaccharide solution
 Disaccharide solution
 Polysaccharide solution
Source: Kaskel, A. (1989). Laboratory biology: Investigating living systems (Teacher Annotated Edition). Merrill, WI:
Merrill Publishing Co.
This copy was made for a fair dealing purpose. Any further distribution must follow the Saskatchewan Polytechnic fair
dealing guidelines.
3
Procedure
1. Fill a beaker half full of water and bring the water to a boil on a hot plate or Bunsen burner.
2. Number three clean test tubes 1, 2 and 3.
3. Using an eyedropper or pipette add the following to the test tubes:
a. Test Tube 1:
30 drops of monosaccharide solution
b. Test Tube 2:
30 drops of disaccharide solution
c. Test Tube 3:
30 drops of polysaccharide solution
4. Add 30 drops of Benedict’s solution to each test tube.
5. Place the three test tubes into the water bath for 5 minutes.
6. Using a test tube holder remove the test tubes from the water bath and place them in a test
tube rack.
7. Observe any color changes in the solutions.
a. Monosaccharides: a change from blue to green, yellow to orange (or red) will occur
b. Disaccharide and Polysaccharide: No colour change.
8. Record your observations in the table below.
Test Tube Number
Carbohydrate Type
Observations Regarding Colour
1
2
3
(3 marks)
2. Iodine Test
Materials
 Test tubes
 Test tube rack
 Test tube holder
 Grease pencil
 Iodine solution
 Droppers or Pipettes
 Monosaccharide solution
 Disaccharide solution
 Polysaccharide solution
Source: Kaskel, A. (1989). Laboratory biology: Investigating living systems (Teacher Annotated Edition). Merrill, WI:
Merrill Publishing Co.
This copy was made for a fair dealing purpose. Any further distribution must follow the Saskatchewan Polytechnic fair
dealing guidelines.
4
Procedure
1. Number three clean test tubes 1, 2 and 3.
2. Using an eyedropper or pipette add the following to the test tubes:
a. Test Tube 1:
30 drops of monosaccharide solution
b. Test Tube 2:
30 drops of disaccharide solution
c. Test Tube 3:
30 drops of polysaccharide solution
3. Add 4 drops of iodine solution to each test tube.
4. Mix the contents of each test tube by gently swirling.
5. Observe any colour changes in the solutions.
a. Monosaccharides and Disaccharides: No colour change.
b. Polysaccharides: a change from rust colour to a deep blue-black
6. Record your observations in the table below.
Test Tube Number
Carbohydrate Type
Observations Regarding Colour
1
2
3
(3 marks)
3. Testing Various Carbohydrates
Materials
 Test tubes
 Test tube rack
 Test tube holder
 Grease pencil
 Benedict`s solution
 Iodine solution
 Droppers or Pipettes
 Hot Plate
 Water
 Beaker
 Apple juice
 Oat solution
 Table sugar solution
 Honey solution
 Powdered sugar solution
Source: Kaskel, A. (1989). Laboratory biology: Investigating living systems (Teacher Annotated Edition). Merrill, WI:
Merrill Publishing Co.
This copy was made for a fair dealing purpose. Any further distribution must follow the Saskatchewan Polytechnic fair
dealing guidelines.
5
Procedure
1. Number five clean test tubes 1 to 5.
2. To each test tube add the following:
a. Test Tube 1: 20 drops of honey
b. Test Tube 2: 20 drops of oat solution
c. Test Tube 3: 20 drops of table sugar solution
d. Test Tube 4: 20 drops of apple juice
e. Test Tube 5: 20 drops of powdered sugar solution
3. Add 30 drops of Benedict’s solution to each test tube.
4. Place all 5 test tubes in a hot water bath for 5 minutes.
5. Remove the test tubes from the bath with a test tube holder and place in the test tube rack.
6. Observe and record any colour changes in the table below.
7. Repeat Step 2.
8. Add 4 drops of iodine solution to each test tube and mix by swirling.
9. Observe and record any colour changes in the table below.
10. Based on these results and the results from Benedict’s Test and theIodine Test, classify each
carbohydrate as a monosaccharide, disaccharide or polysaccharide and record your answers in
the table below.
Substance
(5 marks0
Benedict’s Colour
Iodine Colour
Type of Carbohydrate
Honey
Oats
Table Sugar
Apple Juice
Powdered Sugar
Analysis
1. Name the three categories of carbohydrates studied in this lab.
2. What three elements are present in all carbohydrates?
(1 mark)
(1 mark)
Source: Kaskel, A. (1989). Laboratory biology: Investigating living systems (Teacher Annotated Edition). Merrill, WI:
Merrill Publishing Co.
This copy was made for a fair dealing purpose. Any further distribution must follow the Saskatchewan Polytechnic fair
dealing guidelines.
6
3. Give two examples of sugars that are:
a. Monosaccharides
(1 mark each)
b. Disaccharides
c. Polysaccharides
4. Why are the terms mono, di, and poly used to describe the three types of carbohydrate?
(1 mark)
5. How can you tell by using Benedict’s and iodine solutions if a sugar is a:
a. Monosaccharide
(1 mark each)
b. Disaccharide
c. Polysaccharide
6. A certain sugar has no change in colour when tested with Benedict’s solution. Can you tell
what kind of saccharide it is? Explain your answer.
(2 marks)
7. A certain sugar has no color change in iodine solution. Can you tell what kind of saccharide it
is? Explain your answer.
(2 marks)
8. Give an example of a food that is a:
a. Monosaccharide
(1 mark each)
b. Disaccharide
c. Polysaccharide
Source: Kaskel, A. (1989). Laboratory biology: Investigating living systems (Teacher Annotated Edition). Merrill, WI:
Merrill Publishing Co.
This copy was made for a fair dealing purpose. Any further distribution must follow the Saskatchewan Polytechnic fair
dealing guidelines.
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PROTEINS
II.
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Living things are made of many different molecules with proteins being one important group.
Proteins make up the bulk of all solid material within your body and the bodies’ of other
animals.
Your muscle, skin and inside organs are largely proteins.
Proteins are essential for body growth and repair.
They also make up some hormones which control certain functions in your body.
Enzymes, vital to many biochemical reactions in the body, are made of protein.
Amino Acids – The Building Blocks of Proteins
 Proteins are complex molecules made up of smaller molecules called amino acids.
 There are 20 amino acids found in nature.
 The element Nitrogen is present in all amino acids.
 Below are four amino acids.
Alanine
Valine
Threonine
1. Name the four elements present in these amino acids.
(2 marks)
2. What is the formula for the amino acid:
a. Glycine
(1 mark each)
b. Alanine
c. Valine
d. Threonine
3. How do the formulas for all of the amino acids differ?
(1 mark)
4. Note: That each amino acid contains a segment with a special arrangement of carbon,
oxygen and hydrogen atoms (-COOH). This arrangement is called a carboxyl group. Circle
the carboxyl group on each amino acid above.
(2 marks)
5. Note the left hand side of each amino acid – it has a special arrangement of nitrogen and
hydrogen atoms (-NH2). This arrangement is called an amino group. Use dashed lines to
circle the amino group in each amino acid above.
(2 marks)
Source: Kaskel, A. (1989). Laboratory biology: Investigating living systems (Teacher Annotated Edition). Merrill, WI:
Merrill Publishing Co.
This copy was made for a fair dealing purpose. Any further distribution must follow the Saskatchewan Polytechnic fair
dealing guidelines.
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6. Do carbohydrates have carboxyl groups?
(1 mark)
7. Do carbohydrates have amino groups?
(1 mark)

Amino acids are not protein molecules. They are only the building blocks of protein. Several
amino acids must be chemically joined in a chain to form a protein molecule.

There are thousands of different proteins in living organisms. What makes each protein
different is the order, number, kind and arrangement in space of amino acids joined together.
Identification of Proteins
Materials
 Eye dropper or pipette
 Grease pencil
 Test tubes
 Test tube rack
 Graduated Cylinder
 Sodium Hydroxide
 Copper sulfate
 Egg white (hard boiled)
 Cotton ball
 Hair (light coloured)
 Cream cheese
Procedure
1. Number five clean test tubes 1 to 5.
2. Place the test tubes in the test tube rack.
3. Add the following substances to each test tube:
Test Tube 1: Egg white
Test Tube 2: Cotton ball
Test Tube 3: Hair
Test Tube 4: Cream cheese
4. Add 5 mL of sodium hydroxide to each test tube using the graduated cylinder.
5. Rinse out the graduate cylinder with tap water.
6. Add 5mL of copper sulphate to each test tube using the graduated cylinder.
7. Wait several minutes. Then, in the table below, record the colour of the items in the test
tube.
Source: Kaskel, A. (1989). Laboratory biology: Investigating living systems (Teacher Annotated Edition). Merrill, WI:
Merrill Publishing Co.
This copy was made for a fair dealing purpose. Any further distribution must follow the Saskatchewan Polytechnic fair
dealing guidelines.
9
8. The test used to identify proteins is called the biuret test. A substance containing protein
will turn violet when the biuret test is administered. On the basis of the biuret test you just
did, indicate in the last column of the table below if the substances tested do or don’t
contain protein.
(4 marks)
Substance
Color Of Substance
Is it a Protein or Not?
Egg White
Cotton
Hair
Cream Cheese
Analysis
1. How many amino acids are there?
(1 mark)
2. How are amino acids used by living things?
(1 mark)
3. List four body parts that are made of protein.
(2 marks)
4. Name the four elements present in the amino acids you studied (which are in all amino
acids.
(1 mark)
5. Name the two special groups present in amino acids.
(1 mark)
6. What element is present in proteins (amino acids) that was not present in carbohydrates?
(1 mark)
Source: Kaskel, A. (1989). Laboratory biology: Investigating living systems (Teacher Annotated Edition). Merrill, WI:
Merrill Publishing Co.
This copy was made for a fair dealing purpose. Any further distribution must follow the Saskatchewan Polytechnic fair
dealing guidelines.
10
III.
7. Describe how protein molecules are made.
(1 mark)
8. Explain how one protein differs from another protein.
(1 mark)
9. Describe how to tell if a substance is a protein by using the biuret test.
(1 mark)
FATS
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Fats make up certain parts of your body and are often stored when present in excess and also
serve as an energy source.
To better understand the chemistry of fats, it is helpful to study first the small molecules
which join to make up fats.
Fat molecules are made up of two types of molecules which are called glycerol and fatty acids.
Many different fatty acids exist, but all are similar in several ways. Butyric acid, caproic acid
and lauric acid are examples of fatty acids.
Butyric Acid
Glycerol
1. What elements are present in glycerol?
(1 mark)
Source: Kaskel, A. (1989). Laboratory biology: Investigating living systems (Teacher Annotated Edition). Merrill, WI:
Merrill Publishing Co.
This copy was made for a fair dealing purpose. Any further distribution must follow the Saskatchewan Polytechnic fair
dealing guidelines.
11
2. Are there any elements in glycerol that are not in carbohydrates?
(1 mark)
3. What is the formula for glycerol?
(1 mark)
4. What elements are present in all fatty acids?
(1 mark)
5. What is the chemical formula for butyric acid?
(1 mark)
6. What is the formula for caproic acid?
(1 mark)
7. What is the formula for lauric acid?
(1 mark)
8. How many oxygen atoms are present in each fatty acid?
(1 mark)
9. Note the end of butyric acid containing the oxygen atoms. This special arrangement
of carbon, hydrogen and oxygen is called a carboxyl group. Is the carboxyl group
present in all fatty acids shown?
(1 mark)
10. Give a similarity between glycerol and fatty acids.
(1 mark)
11. Do fatty acids and glycerol both contain a carboxyl group?
(1 mark)
A fat molecule consists of 1 glycerol and 3 fatty acid molecules joined together.
1. To form a fat molecule 3 OH from the glycerol molecule and 3 H from the fatty acids
would have to be removed. What chemical substance is formed when the left over
OH and H are joined together?
(1 mark)
Source: Kaskel, A. (1989). Laboratory biology: Investigating living systems (Teacher Annotated Edition). Merrill, WI:
Merrill Publishing Co.
This copy was made for a fair dealing purpose. Any further distribution must follow the Saskatchewan Polytechnic fair
dealing guidelines.
12
2. A change in type of fatty acid results in a different type of fat molecule. What
molecule remains unchanged in all fats?
(1 mark)
Brown Paper Test
Materials
 Brown paper
 Eye dropper or pipette
 Oil
 Water
 Pen or pencil
 Vinegar
 Margarine
 Mayonnaise
 Cream Cheese
Procedure
1. On separate pieces of brown paper rub one drop of oil and one drop of water and
label the spots. Oil is a fat whereas water is not.
2. Allow the paper to dry for a few minutes.
3. Hold the paper toward the light. If light passes through, a translucent spot has
formed.
4. Examine the pieces of paper to check for0 translucent spots. Fats should give a
translucent spot and water should not.
5. Perform the brown paper test on each of the following substances (use only small
amounts of each) and record your observations in the table below.
a. Mayonnaise
b. Margarine
c. Vinegar
d. Cream cheese
Substance
(4 marks)
Translucent Spot on
Paper (yes or no)
Fat Present
(yes or no)
Mayonnaise
Margarine
Vinegar
Cream Cheese
Source: Kaskel, A. (1989). Laboratory biology: Investigating living systems (Teacher Annotated Edition). Merrill, WI:
Merrill Publishing Co.
This copy was made for a fair dealing purpose. Any further distribution must follow the Saskatchewan Polytechnic fair
dealing guidelines.
13
Analysis
1. Name the types of molecules and the number of each type needed to form a fat
molecule.
(2 marks)
2. List two ways in which a fatty acid molecule differs from glycerol.
(2 marks)
3. Did any of the substances tested not contain fat? If so which one(s)? (1 mark)
Total Marks: 86
Source: Kaskel, A. (1989). Laboratory biology: Investigating living systems (Teacher Annotated Edition). Merrill, WI:
Merrill Publishing Co.
This copy was made for a fair dealing purpose. Any further distribution must follow the Saskatchewan Polytechnic fair
dealing guidelines.