Chapter 8

What structural features do a triacylglycerol and a phosphatidyl ethanolamine have in common? How do the structures of these two types of lipids differ?

What structural features do a sphingomyelin and a phosphatidyl choline have in common? How do the structures of these two types of lipids differ?

You have just isolated a pure lipid that contains only sphingosine and a fatty acid. To what class of lipids does it belong?

Succulent plants from arid regions generally have waxy surface coatings. Suggest why such a coating is valuable for the survival of the plant.

In the produce department of supermarkets, vegetables and fruits (cucumbers are an example) have been coated with wax for shipping and storage. Suggest a reason why this is done.

In the preparation of sauces that involve mixing water and melted butter, egg yolks are added to prevent separation. How do the egg yolks prevent separation? Hint: Egg yolks are rich in phosphatidylcholine (lecithin).

When water birds have had their feathers fouled with crude oil after an oil spill, they are cleaned by rescuers to remove the spilled oil. Why are they not released immediately after they are cleaned?

Which of the following lipids are not found in animal membranes? (a) Phosphoglycerides (b) Cholesterol (c) Triacylglycerols (d) Glycolipids (e) Sphingolipids

Which of the following statements is (are) consistent with what is known about membranes? (a) \(\mathrm{A}\) membrane consists of a layer of proteins sandwiched between two layers of lipicls. (b) The compositions of the inner and outer lipid layers are the same in any individual membrane. (c) Membranes contain glycolipids and glycoproteins. (d) Lipid bilayers are an important component of membranes. (e) Covalent bonding takes place between lipids and proteins in most membranes.

Why might some food companies find it economically advantageous to advertise their product (for example, triacylglycerols) as being composed of polyunsaturated fatty acids with trans double bonds?