Lesson 6 – Lipids, Fatty Acids, Triglycerides, and Phospholipids
SCI260 – Introduction to Biochemistry
1. Describe (in words) the overall structure of a lipid bilayer.
2. What are the properties (i.e., characteristics) of the lipid bilayer of a cell that
make it impermeable to ions and most molecules?
3. Describe the role of cholesterol in maintaining the fluidity of the lipid bilayer of a
4. The triglycerides in animals tend to be solids (i.e., fats) at room temperature
whereas the triglycerides in plants tend to be liquids (i.e., oils) at room
temperature. Based on this fact, what can you conclude about the characteristics
of the fatty acids in animal triglycerides compared to the fatty acids in plant
5. Peanut oil contains a high percentage of monounsaturated triglycerides whereas
vegetable oil contains a higher percentage of polyunsaturated triacylglycerols. A
bottle of peanut oil and a bottle of vegetable oil are stored in a pantry with an
outside wall. During a cold spell, the peanut oil freezes, but the vegetable oil
remains liquid. Explain why.
6. How many molecules of ATP are generated when stearic acid (i.e., stearate), an
18-carbon saturated fatty acid, is completely oxidized via the beta-oxidation
pathway in the mitochondria?
7. Which of the following fatty acids below are essential for humans? *Select one or
a) Oleic acid
b) Linoleic acid
c) Linolenic acid
d) Palmitoleic acid
e) Eicosapentaenoic acid (EPA)
8. Refer to Question 7, look up the structures of each fatty acid that is essential and
explain why they are essential for humans?
9. Are trans fatty acids saturated or unsaturated?
10. Provide four (4) examples of foods that contain trans fatty acids.
You may use your textbook and/or the internet to assist you. You will earn 10 points for
correctly answering each question (maximum points earned = 100 points).