Chapter 11 Review Quiz

Lipids and Membranes

. The double bonds of unsaturated fatty acids are very labile to oxidation. Spontaneous combustion of the drying oils in older oil-based paints posed a hazard for homeowners, as the residue of drying oil could easily catch fire and ignite the home. In sensational magazines, we occasionally read accounts of a person who caught fire and died from spontaneous combustion.
How likely is this to occur?

. Hydrogenation of an unsaturated fatty acid usually results in a compound having:

. Many cellular processes such as exocytosis depend upon membrane fusion. Membrane fusion in turn depends upon the presence of specialized proteins, especially transmembrane proteins called:

. Both ω-3 and ω-6 fatty acids are essential for health. If one wanted a diet rich in both, he or she should choose:

. Sperm whales possess large cavities in their heads; the lipid-rich contents of these cavities are one of the reasons these whales are still sought. In particular, the cavity contains a lipid which is highly effective as an additive for automatic transmission fluid. The compound, highly resistant to the shear forces between gear teeth, is made up of a long chain lipid alcohol and a long chain fatty acid joined by an ester bond. You would most correctly classify this as a:

. Fatty acids are often transported attached to albumin. In the absence of lipoprotein or albumin, lysophospholipid molecules may form structures in aqueous solution called:

. Individual classes of lipids may include molecules which have very different functional groups, but a characteristic common to all is that they:

. One of the most endearing characteristics of biomembranes is that they are relatively waterproof and self-sealing. In order to maintain their reputation as self-sealers, biomembranes need a supply of this metallic ion:

. Cystic fibrosis results from an inability of the body to transport a fundamentally important substance. Which one?

. Phospholipids are similar in that they all contain a diacylglycerol portion attached to a phosphate, and occasionally to some other functional group such as ethanolamine or sphingosine. In addition to their nonpolar character, all phospholipids have another physical property. Which one?

. If you were handed a sample of a white, greasy substance and asked to determine whether it were a triacylglycerol or a fatty acid, you could do so easily by:

. Although water can move across cell membranes in response to changes in osmotic pressure, cellular membranes usually have a distinct nonpolar character, making it possible for them to retain water and to bar polar molecules from passage. Certain cells, such as those in kidney tubules, must allow ready passage of water molecules. In order to do so, the cells possess special molecular structures called:

. Both thromboxanes and leukotrienes are lipids, but they differ structurally in one major respect. What is it?

. Many persons are advised by their physicians to include some ω-3 fatty acids (such as those found in fish oil or in the meat of cold-water fish) in their diets. The omega designation tells us where the double bonds are placed in a structure, and specify the carbon at which the double bond begins. The ω number is the number of carbons from the terminal end of the fatty acid (recall that the delta designation told you the number of the carbon where the double bond began, numbering in from the -COOH end). Which of the following is an ω-3 fatty acid?

. A popular saying once maintained that "You are what you eat." On a Midwestern farm, a boy was assigned to feed a blind pig, but was unable to open the door of the corn bin, so fed the pig entirely on soybeans. When the pig was butchered, the bacon, instead of being red and white, was red and clear, and the lard, when cooked out of the fatty tissue or "rendered," never congealed into a solid, but remained a liquid. The cause of this phenomenon was:

. Which of the following transport processes requires no energy?

. The bites of Loxosceles reclusus, the brown recluse spider, and its cousin, Latrodectus mactans, the black widow, can cause very painful and dangerous ulcers. The injury is caused by an enzyme which lyses the second fatty acid reside of lecithin, producing a phospholipid called lysolecithin. Lysolecithin cuts the membrane of erythrocytes, releasing hemoglobin, which can then not release oxygen. The lysolecithin is dangerous to erythrocytes because:

. If you centrifuge a sample of blood or of liver homogenate, some lipids may rise to the surface, forming a layer or cake of lipid. The lipid fraction most likely to collect atop the aqueous liquid at the bottom of the lipid fraction is:

. In general, you'd probably be healthier if your blood plasma contained higher levels of:

. In the system of nomenclature of fatty acids, the carbon next to the carboxylic acid group is designated the α- carbon. The carbon second from the carboxylic acid group is the β- carbon, the fourth carbon in the chain is the γ- carbon, and so on. But there is one carbon in the chain which always has the same Greek letter as its designation, no matter how far it is from the carboxylic acid residue. Which one?

. Triacylglycerols found in plants are more likely than those in animals to be:

. Most naturally-occurring fatty acids:

. Isoprene (2-methyl-1,3-butadiene) is a compound found in many natural products such as latex which can polymerize to form substances such as rubber. In addition, combinations of isoprene such as dimers, tetramers or larger, modified molecules make up a class of biomolecules known as:

. Prior to hydrogenation of a lipid, chemists need to determine the iodine number in order to predict the average number of double bonds in each molecule. The iodine number is defined as the number of grams of iodine which can be added to the double bonds in 100 g of lipid. Which of the following would have the highest iodine number?

. Which of the following is not an eicosanoid?

Back to top