Name: ____________________________
Block: ___________
Let’s Build Lipids!
Introduction
Lipids are a diverse group of chemical compounds that are related by their
insolubility in water. Lipids include phospholipids, sterols, and
triglycerides.
Phospholipids are important parts of cell membranes. Sterols such as
cholesterol form vital biological compounds including hormones.
Triglycerides store energy, protect certain organs, transport fatsoluble vitamins, and help insulate the body. Triglycerides are the most
common type of lipid found in the body and in foods. Triglycerides include
the edible fats and oils in our diets - substances such as olive oil, corn oil,
peanut oil, butterfat, and lard. Triglycerides that are solid or semisolid at
room temperature are classified as fats, and occur predominantly in
animals. Those triglycerides that are liquid are called oils and originate
chiefly in plants. Fats and oils are made up of two different kinds of
molecules, glycerol and fatty acids.
In this activity, you will
(a) examine the molecular structure of glycerol and
fatty acids.
(b) use structural formulas and molecular models of glycerol
and fatty acids to determine how these molecules join together to form fats
and oils.
The Structure of Glycerol
The molecular formula for Glycerol is: CH2OHCHOHCH2OH.
What type of molecule is glycerol? How do you know?
Draw the structural formula of Glycerol:
Now, build it!
Using the Play-Doh and toothpicks, build a model of glycerol using the
structural formula you constructed above.
Building Up and Breaking Down
Fatty acids are the second kind of molecule found in triglycerides.
Saturated fatty acids have no double bonds between the carbon atoms of
the fatty acid chain and all other bonds are attached to hydrogen atoms. An
unsaturated fatty acid does have one or more double bonds between
carbon atoms.
Now, build it!
Carry out DEHYDRATION SYNTHESIS for the following saturated and
unsaturated fats with Play-Doh. Build the individual molecules first and
then put the molecules together via dehydration synthesis:
1. Glycerol + 3(CH3CH2CH2COOH)
What are your products? ___________________ + ___________
How many water molecules are formed when one triglyceride molecule is
produced? _____________
2. Glycerol + 2 CH3CH2CH2COOH + 1 CH3CH2CHCHCH2COOH
What are your products? ___________________ + ___________
How many water molecules are formed when one triglyceride molecule is
produced? _____________
Carry out HYDROLYSIS for each of the previous structures you built
above with Play-Doh. Put together the entire triglyceride first AND THEN
break it apart.
1. What are your products? ___________________ + ___________
How many water molecules were used to form the triglyceride product?
_____________
2. What are your products? ___________________ + ___________
How many water molecules were used to form the triglyceride product?
_____________