Welcome to the Lipids debriefing.

Answer the questions in the spaces provided. If necessary, click on the Check buttons when you are finished with each problem.

1. On the paper structure of distearyl phosphatidyl choline shown below, click on the following groups:

Glycerol

Glycerol is the "scaffold" phospholipids are constructed around.

Fatty acid(s)

Fatty acids are long, linear hydrocarbons.

Head Group

The head group is polar and contains phosphorus.

2. From the following molecules, check any that are amphiphiles.

Dodecane
Sodium dodecyl sulfate (SDS) Adenosine Triphosphate (ATP) Cholesterol
Correct! Cholesterol and SDS both have hydrophobic and polar parts. Thus they are amphiphiles.
Does ATP have a hydrophobic part?
Does dodecane have a polar part?
Correct! But is there another?

3. Which of the following structures do you think amphiphilic molecules could form in water?

Hexagonal Type I Hexagonal Type II Micelle
Correct! The polar parts are on the outside of these two structures, so they can interact with water, which is also polar. The hydrophobic parts are kept away from water.
Correct! But is there another?
If water surrounds the structures, what part will it touch?

4. If the solvent were hexane instead, which of the structures above do you think would form?

Hexagonal Type I Hexagonal Type II Micelle
Correct! In the hydrophobic solvent hexane, the hydrophobic parts will orient themselves outward, burying the polar parts inside the cylinders. Any water that is present will reside there.
What parts, hydrophobic or polar, would hexane interact with?

Congratulations!

You have completed the Lipids module.

Click on the Lipids icon below to return to the Biomolecules Gateway page.