Chemistry of Lipids
Name: _________________________
All living things are composed of many different kinds of chemical molecules. Two very
important chemical molecules are lipids and proteins. Both make up parts of living cells.
Lipids are a part of all cellular membranes. They also may be stored within a cell as an energy
source.
In this investigation, you will
a. learn that all lipid molecules are made up of two kinds of smaller molecules, glycerol
and fatty acids.
b. use structural formulas and models of glycerol and fatty acids to determine how
these molecules join together to form lipid molecules.
Lipids
To better understand the chemistry of lipids, it is helpful to study first the small molecules
which join to make up lipids. Lipid molecules are made up of two different kinds of chemical
molecules. These are glycerol and fatty acids.
Part A. Glycerol
Examine the structural formula of glycerol to the right.
1. What elements are present in glycerol?
2. Are there any elements in glycerol that are not in carbohydrates?
3. What is the chemical formula for glycerol?
(Add the number of atoms of each element and record the totals.)
C____ H____ O____
4. As in carbohydrates, are there twice as many hydrogen atoms as oxygen atoms in
glycerol?
Part B. Fatty Acids
The second kind of molecule which is part of a lipid is a fatty acid. Many different fatty acids
exist, but all are similar in several ways. Butyric acid, caproic acid, and lauric acid are examples
of fatty acids.
Examine the structural formulas for the above three molecules.
6. What 3 elements are present in all fatty acids?
7. a) What is the chemical formula for butyric fatty acid? C____ H____ O____
b) What is the chemical formula for caproic fatty acid? C____ H____ O____
c) What is the chemical formula for lauric fatty acid? C____ H____ O____
8. Are there twice as many hydrogen atoms as oxygen atoms in a fatty acid?
9. Note the end of butyric acid containing the oxygen atoms. This special
end arrangement of carbon, hydrogen and oxygen is called a carboxyl
group. Is the carboxyl group present in all fatty acids shown?
10. a) List a similarity between glycerol and fatty acids.
b) Do fatty acids and glycerol both contain a carboxyl group?
Analysis Questions
1.
a) What two molecule types are needed to form a molecule of fat?
b) How many of each type of these molecules are needed to form a molecule of fat?
2. What chemical elements are found in all fats?
3. List two ways that fatty acids differ from glycerol