Online Ch 17

What is the biological function of sphingomyelin? It decreases blood clot formation. It is an important structural lipid component of nerve cell membranes. It aids in the emulsification and digestion of lipids. It regulates the fluidity of the cell membrane.

It is an important structural lipid component of nerve cell membranes.

What is the role of cholesterol in biological membranes? It serves as a "marker" that identifies a cell to other cells. It provides shape to the cell. It acts as a molecular signal that allows cells to communicate with each other. It regulates the fluidity of the membrane.

It regulates the fluidity of the membrane.

Why are sphingomyelins amphipathic? They behave like hormones. They have a polar head and a nonpolar tail. They have no charge. They aid in the suspension of triglycerides in water.

They have a polar head and a nonpolar tail.

What are the structural differences between triglycerides (triacylglycerols) and phospholipids? a. Triglycerides consist of three fatty acids esterified to the three hydroxyl groups of glycerol. b. Triglycerides consist of two fatty acids esterified to two hydroxyl groups of glycerol. c. Phospholipids consist of three fatty acids esterified to glycerol. d. Phospholipids consist of two fatty acids esterified to glycerol and a phosphoryl group esterified to the third hydroxyl group.

a, d

What do the terms omega-3 (ω-3) and omega-6 (ω-6) indicate about the structures of the fatty acids in those classifications? a. In ω-6 fatty acids, the double bond nearest the ω methyl group is six carbons along the chain. b. In ω-6 fatty acids, the carbon backbone is six carbons in length. c. In ω-3 fatty acids, the double bond nearest the ω methyl group is three carbons along the chain. d. In ω-3 fatty acids, the carbon backbone is three carbons in length.

a,c

As the length of the hydrocarbon chain of saturated fatty acids increases, what is the effect on the melting point? a. melting point increases b. melting point decreases c. melting point remain constant d. melting point varies randomly

a. melting point increases

What is the basic structure of a biological membrane? A. The hydrophilic head groups are packed in the center. B. The hydrophilic head groups are exposed on the inner and outer surfaces. C. The hydrophobic hydrocarbon tails are exposed on the inner and outer surfaces. D. The hydrophobic hydrocarbon tails are packed in the center.

b, d

What is the difference between a saturated and unsaturated fatty acid? a. In saturated fatty acids, there is at least one carbon-to-carbon double bond. b. In saturated fatty acids, each carbon is bound to the maximum number of hydrogens. c. In unsaturated fatty acids, each carbon is bound to the maximum number of hydrogens. d. In unsaturated fatty acids, there is at least one carbon-to-carbon double bond.

b, d

What is the biochemical basis for the effectiveness of aspirin in decreasing the inflammatory response? a. It promotes the synthesis of prostaglandins. b. It inhibits the synthesis of prostaglandins. c. It inhibits the absorption of vitamins. d. It promotes the synthesis of steroid

b. It inhibits the synthesis of prostaglandins

What is one function of the essential fatty acids? a. stimulate inflammatory response b. cause the renal blood vessels to dilate c. storage of energy d. biosynthesis of arachidonic acid

d. biosynthesis of arachidonic acid

A wax found in beeswax is myricyl palmitate. What fatty acid and what alcohol are used to form this compound? Fatty acid: Alcohol:

fatty: palmitic acid alcohol : myricyl alcohol

Select the single best answer. How will the properties of a biological membrane change if the fatty acid tails of the phospholipids are converted from saturated to unsaturated chains? Cell-to-cell communication will decrease. The fluidity of the membrane will decrease. Cell-to-cell communication will increase. The fluidity of the membrane will increase.

fluidity of the membrane will increase

What is the function of unsaturation in the hydrocarbon tails of membrane lipids? energy source catalysis increased fluidity structural support

increased fluidity

What are the four major types of plasma lipoproteins? cholesterols very high-density lipoproteins low-density lipoproteins high-density lipoproteins chylomicrons triglycerides phospholipids very low-density lipoproteins proteins lysosomes

low density lipoproteins high density lipoproteins chylomicrons very low density lipoproteins

How is LDL taken into cells? passive diffusion receptor-mediated endocytosis exocytosis

receptor mediated endocytosis

At room temperature, what would be the physical state of a triglyceride with three saturated fatty acid tails? liquid gas solid

solid

What are two major types of sphingolipids? sphingomyelins glycosphingolipids steroids

sphingomyelins glycosphingolipids