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POGIL Biology III – Macromolecules of the Cell - Lipids
The cell is constructed of four basic kinds of large polymer (macromolecule) – protein,
lipid, carbohydrate, and nucleic acid. This exercise explores our current model of the
lipid.
Model 1 – The TRIGLYCERIDE
Model 2 – Phospholipids and membranes
Using the diagrams above, your textbook, and your note set, answer the following
questions.
1. In model 1, what does the C stand for? The O? The H? What does the
straight line between atoms represent?
2. In model 1, describe the interaction between carbon and carbon, carbon
and hydrogen and carbon and oxygen atoms in a triglyceride.
3. In model 1, which part (atoms) of the triglyceride molecule would you
assign a ? A 
4. In model 1, the triglyceride is formed by a chemical reaction between
which two chemicals?
5. Would you expect a chemical that reacts with O-H groups to react with a
triglyceride? Glycerol?
6. Using model 2 as a resource, with a diagram show which is the
hydrophobic part of a triglyceride. The hydrophilic?
7. Model 2 shows a phospholipid called phosphatidyl choline. Why is that
lipid referred to as a phospholipid?
8. List the different parts of a phospholipid.
9. Which part of the phospholipid interacts with water?
10. Describe the similarities and differences between phospholipids and
triacylglycerides.
11. In the phospholipid bilayer of Model 2, what do the light gray wiggly
protrusions, or tails, represent? The spheres?
12. Why are the gray tails interacting with each other rather than with the
polar head groups (spheres)?
13. Cholesterol is a lipid that exists in the membranes of animal cells. Where
in the lipid bilayer do you think it resides?
14. Find the structure of cholesterol in your textbook. How would you expect
addition of several oxygen atoms and phosphate molecules to cholesterol
affect its ability to embed in the lipid bilayer?