Problem 1
Roles of various phospholipids include all of the following except A. cell-cell recognition. B. a surfactant function in lung. C. activation of certain membrane enzymes. D. signal transduction. E. mediator of hypersensitivity and acute inflammatory reactions.
Problem 2
CDP-X (where \(X\) is the appropriate alcohol) reacts with 1,2 -diacylglycerol in the primary syntheric pathway for A. phosphatidylcholine. B. phosphatidylinositol. C. phosphatidylserine. D. all of the above. E. none of the above.
Problem 3
Plasmalogens differ from other membrane lipids in that they A. do not contain phosphorus. B. are found primarily in the inner mitochondrial membrane. C. have an alkene in ether linkage at the sn-1 position rather than a fatty acyl group. D. always contain a bound serine. E. contain a sugar molecule esterificd to the phosphate.
Problem 4
Bile acids differ from their precursor cholesterol in that they A. are not amphipathic. B. contain an ionizable carboxyl group. C. contain less oxygen. D. are synthesized primarily in intestine. E. contain more double bonds.
Problem 5
A ganglioside may contain all of the following except A. a ceramide structure. B. glucose or galactose. C. phosphate. D. one or more sialic acids. \(\mathbf{E},\) sphingosine
Problem 6
Phosphatidylinositols A. are neutral phospholipids. B. are found primarily in mitochondrial membrane. C. release \(\mathrm{Ca}^{2+}\) from the endoplasmic reticulum. D. can serve to anchor glycoproteins to cell surfaces. E. are the major surfactants maintaining normal lung function.
Problem 7
Prostaglandin synthase, a bifunctional enzyme, A. catalyzes the rate-limiting step of prostaglandin synthesis. B. is inhibited by anti-inflammatory steroids. C. contains both a cyclooxygenase and a peroxidase component. D. produces \(\mathrm{PGG}_{2}\) as the end product. E. uses as substrate the pool of free arachidonic acid in the cell.
Problem 8
Leukotricnes A. synthesis begins with the addition of a hydroperoxy group to arachidonic acid. B. are inactivated by conversion to HPETEs. C. have an internal ring structure. D. are highly unstable, lasting only a fcw minutes. E. are converted to lipoxins.
Problem 9
In biosynthesis of cholesterol, A. 3 -hydroxy-3-methyl glutaryl CoA (HMG CoA) is synthesized by mitochondrial HMG CoA synthase. B. HMG CoA reductase catalyzes the rate-limiting step. C. the conversion of mevalonic acid to farnesyl pyrophosphate proceeds via condensation of three molecules of mevalonic acid. D. condensation of two farnesyl pyrophosphates to form squalene is freely reversible. E. conversion of squalene to lanosterol is initiated by formation of the fused ring system, followed by addition of oxygen.
Problem 10
Cholesterol present in LDL (low-density lipoproteins) A. binds to a cell receptor and diffuses across the cell membrane. B. when it enters a cell, suppresses activity of ACAT (acyl CoAcholesterol acyl transferase). C. once in the cell, is converted to cholesteryl esters by LCAT (lecithin- cholesterol acyl transferase). D. once it has accumulated in the cell, inhibits replenishment of LDL receptors. E. represents primarily cholesterol that is being removed from peripheral cells.
