Chp 10

Front 1

Which of the following molecules or substances contain, or are derived from, fatty acids? A) Beeswax B) Prostaglandins C) Sphingolipids D) Triacylglycerols E) All of the above contain or are derived from fatty acids.

Back 1

e

Front 2

Triacylglycerols are composed of:A) a glycerol backbone.B) three fatty acids.C) amide linkages between the fatty acids and the glycerol.D) A and B above.E) A, B, and C above.

Back 2

d

Front 3

Which of the following is not a consequence of partial hydrogenation of vegetable oils?A) Longer shelf lifeB) Lower melting temperatureC) Reduction of some cis double bonds to single bondsD) Conversion of some cis double bonds to trans double bondsE) Increased risk of cardiovascular disease upon consumption by humans

Back 3

b

Front 4

Biological waxes are all: A) triesters of glycerol and palmitic acid.B) esters of single fatty acids with long-chain alcohols.C) triesters of glycerol and three long chain saturated fatty acids.D) sphingolipids.E) None of the above

Back 4

b

Front 5

Which of the following statements is true of lipids? A) Many contain fatty acids in ester or amide linkage. B) Most are simply polymers of isoprene. C) Testosterone is an important sphingolipid found in myelin. D) They are more soluble in water than in chloroform.E) They play only passive roles as energy-storage molecules

Back 5

b

Front 6

Which of the following statements concerning fatty acids is correct? A) A fatty acid is the precursor of prostaglandins. B) Phosphatidic acid is a common fatty acid. C) Fatty acids all contain one or more double bonds.D) Fatty acids are a constituent of sterols.E) Fatty acids are strongly hydrophilic.

Back 6

a

Front 7

Which of the following contains an ether-linked alkyl group? A) Cerebrosides B) GangliosidesC) Phosphatidyl serine D) Platelet-activating factor E) Sphingomyelin

Back 7

d

Front 8

Sphingosine is not a component of: A) cardiolipin. B) ceramide.C) cerebrosides. D) gangliosides. E) sphingomyelin.

Back 8

a

Front 9

Which of the following statements about membrane lipids is true? A) Glycerophospholipids are found only in the membranes of plant cells.B) Glycerophospholipids contain fatty acids linked to glycerol through amide bonds. C) Lecithin (phosphatidylcholine), which is used as an emulsifier in margarine and chocolate, is a sphingolipid. D) Some sphingolipids include oligosaccharides in their structure. E) Triacylglycerols are the principal components of erythrocyte membranes.

Back 9

d

Front 10

Which of the following is not a glycerophospholipid?A) PhosphatidylcholineB) PhosphatidylethanolamineC) PhosphatidylserineD) CardiolipinE) Ceramide

Back 10

e

Front 11

Which of the following is true of sphingolipids? A) Cerebrosides and gangliosides are sphingolipids.B) Phosphatidylcholine is a typical sphingolipid. C) They always contain glycerol and fatty acids. D) They contain two esterified fatty acids. E) They may be charged, but are never amphipathic.

Back 11

a

Front 12

A compound containing N-acetylneuraminic acid (sialic acid) is: A) cardiolipin. B) ganglioside GM2. C) phosphatidylcholine. D) platelet-activating factor.E) sphingomyelin.

Back 12

b

Front 13

Which of the following answers is not true?A) Phospholipase A1 hydrolyzes the fatty acid from the 1-position on the glycerol backbone.B) Phospholipase B1 hydrolyzes the fatty acid from the 2-position on the glycerol backbone.C) Phospholipase C hydrolyzes the complete phospho-head group from the glycerol backbone.D) Phospholipase D hydrolyzes just the head group from the phospho-glycerol backbone.

Back 13

b

Front 14

Which of the following statements about sterols is true? A) All sterols share a fused-ring structure with four rings. B) Sterols are found in the membranes of all living cells. C) Sterols are soluble in water, but less so in organic solvents such as chloroform.D) Cholesterol is the principal sterol in fungi. E) The principal sterol of animal cells is ergosterol.

Back 14

a

Front 15

Fatty acids are a component of: A) carotenes. B) cerebrosides. C) sterols. D) vitamin D. E) vitamin K.

Back 15

b

Front 16

Which of the following is not true of sterols? A) Cholesterol is a sterol that is commonly found in mammals. B) Sterols are commonly found in bacterial membranes. C) Sterols are more common in plasma membranes than in intracellular membranes (mitochondria, lysosomes, etc.). D) Serols are precursors of steroid hormones. E) Sterols have a structure that includes four fused rings.

Back 16

b

Front 17

Which of the following best describes the cholesterol molecule? A) Amphipathic B) Nonpolar, charged C) Nonpolar, uncharged D) Polar, charged E) Polar, uncharged

Back 17

a

Front 18

Tay-Sachs disease is the result of a genetic defect in the metabolism of: A) gangliosides. B) phosphatidyl ethanolamine.C) sterols. D) triacylglycerols. E) vitamin D.

Back 18

a

Front 19

An example of a glycerophospholipid that is involved in cell signaling is: A) arachidonic acid. B) ceramide. C) phosphatidylinositol. D) testosterone. E) vitamin A (retinol).

Back 19

c

Front 20

Non-steroidal anti-inflammatory drugs (NSAIDS) like aspirin and ibuprofen act by blocking production of: A) biological waxes B) prostaglandinsC) sphingolipids D) vitamin D E) none of the above

Back 20

b

Front 21

Which of the following is not a fat-soluble vitamin? A) A B) C C) D D) E E) K

Back 21

b

Front 22

Identify the molecule(s) derived from sterols. A) Arachidonic acid B) Gangliosides C) Phosphatidylglycerol D) Prostaglandins E) Cortisol

Back 22

e

Front 23

Which of the following techniques is not commonly used to analyze lipid composition?A) Selective extraction using apolar solventsB) Adsorption chromatographyC) X-ray crystallographyD) Hydrolysis using enzymes with specificity for certain linkagesE) Mass spectroscopy

Back 23

c

Front 24

Circle the fatty acid in each pair that has the higher melting temperature.(a) 18:19 18:29,12(b) 18:0 18:19(c) 18:0 16:0

Back 24

(a) 18:19; (b) 18:0; (c) 18:0

Front 25

Describe the dependence of the melting point of a fatty acid upon (a) chain length and (b) unsaturation; (c) explain these dependencies in molecular terms.

Back 25

All other things being equal, (a) the longer the acyl chain, the higher the melting temperature; and (b) the more unsaturation, the lower the melting temperature. (c) The melting temperature is a measure of the thermal energy needed to break the intermolecular interactions that stabilize the “solid” form of a lipid, which depends on how well the individual lipid molecules fit into the nearly crystalline array of lipids. When a shorter acyl chain lies between two longer chains in a nearly crystalline array of lipid molecules, there is a cavity at the end of the short acyl group that allows freer motion to the neighboring acyl chains. A cis double bond introduces a “kink” into the acyl chain so that it does not pack as easily with its straighter neighbors.

Front 26

What is the effect of a double bond on fatty acid structure

Back 26

Most double bonds in fatty acids are in the cis configuration. This results in a rigid bend in the hydrocarbon chain. (See Fig. 10-1, p. 345.)

Front 27

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Back 27

fdfdfdfd

Front 28

What is the most significant chemical difference between triacylglycerols and glycerophospholipids that leads to their different functions?

Back 28

Three fatty acids are esterified to glycerol. (b) Triacylglycerols are uncharged and insoluble in water. They form lipid droplets within adipocytes, which do not contribute to the osmolarity of the cytosol in those cells, and do not require any water of hydration.

Front 29

What is the most significant chemical difference between triacylglycerols and glycerophospholipids that leads to their different functions?

Back 29

Triacylglycerols are nonpolar hydrophobic molecules that can be stored in specialized nonaqueous cellular compartments. Glycerophospholipids are amphipathic molecules that can serve as structural components of membranes, which have hydrophilic and hydrophobic regions.

Front 30

Describe three functions of triacylglycerols in mammals and one function in higher plants.

Back 30

Triacylglycerols provide mammals with (1) stored fuel, (2) insulation, and (3) a source of metabolic water. In some animals, such as camels and desert rats, the oxidation of stored lipids provides water; in hibernating animals, oxidation of stored lipids generates heat to maintain body temperature (see Chapter 4). In plants, oxidation of the triacylglycerols stored in seeds provides the energy and precursors for biosynthetic processes during germination, before photosynthetic mechanisms become functional.

Front 31

What are the chemical components of a biological wax, and what is their general structure?

Back 31

A wax consists of a long-chain fatty acid in ester linkage with a long-chain fatty alcohol. (See Fig. 10-6.)

Front 32

Draw the structure of phosphatidylserine in the ionic form it would have at pH 7.

Back 32

: For this structure, see Fig. 10-9. At neutral pH, there is a charge on the phosphate group, and serine is in the zwitterionic form; it has a protonated amino group and an ionized carboxyl group.

Front 33

Give the structure of phosphatidylethanolamine containing one palmitate and one oleate. Show the ionic form expected at pH 7. How many ester bonds are there in this compound?

Back 33

See Fig. 10-9 for the phospholipid structure and Table 10-1,for the structures of the fatty acids. There are two carboxylate esters and two phosphate esters (one phosphodiester) in the molecule.

Front 34

Draw the structure of phosphatidylcholine. Circle the part of the molecule that is polar and draw an arrow to the part that is nonpolar.

Back 34

For this structure, see Fig. 10-9. At neutral pH, there is a negative charge on the phosphate group, and the quaternary amino group of choline carries a fixed positive charge; this entire phosphorylcholine moiety is polar. The acyl chains attached to glycerol are the nonpolar part of the molecule.

Front 35

Show the basic structure of all glycerophospholipids.

Back 35

All glycerophospholipids have two fatty acids in ester linkage with C-1 and C-2 of glycerol; often, the fatty acid at C-1 is saturated and that at C-2 is unsaturated. C-3 of glycerol is joined to an alcohol-containing head group through a phosphodiester linkage, which is negatively charged at neutral pH. (See Fig. 10-9.)

Front 36

What chemical features distinguish a plasmalogen from a common glycerophospholipid?

Back 36

(1) The long-chain acyl group attached to C-1 of glycerol is ether-linked in a plasmalogen but is an ester-linked fatty acyl group in typical glycerophospholipids. (2) There is a double bond between C-1 and C-2 of this fatty acyl chain in plasmalogens, but not in other phospholipids. (See Fig. 10-10.)

Front 37

Show the structure of sphingosine and indicate the relationship between sphingosine and ceramide.

Back 37

The structure of sphingosine is shown in Fig. 10-13, which also shows that the attachment of a fatty acyl group to sphingosine in amide linkage converts it to ceramide.

Front 38

What chemical features distinguish a cerebroside from a ganglioside?

Back 38

A cerebroside has a single sugar residue joined to ceramide; a ganglioside has an oligosaccharide joined to ceramide. (See Fig. 10-13.)

Front 39

role of thromboxane

Back 39

blood clotting

Front 40

steriod role

Back 40

intra-tissue messengers

Front 41

vitamin a role

Back 41

necessary for sight

Front 42

prostaglandins role

Back 42

mediates pain and inflamation

Front 43

sphingolipids

Back 43

important component of mylein membranes

Front 44

vitamin e role

Back 44

reducing agent

Front 45

The venom of some rattlesnakes contains phospholipase A2. a) Explain why a snake bite causes rapid pain and inflammation. b) Based on your biochemical understanding of the mechanism of the pain, suggest a possible treatment. c) If too much phospholipase A2 enters the bloodstream, the significant accumulation of one of the products of the reaction acts as a powerful detergent, causing the lysis of red blood cells and potential death. What is this dangerous product and what makes it such a good detergent?

Back 45

a) Phospholipase A2 cleaves the 2-position of the phospholipids. The 2-position often contains arachidonic acid, which is converted to prostaglandins via the action of cyclooxygenase (COX). Increased prostaglandins yield pain and inflammation. b) Blocking the activity of COX using NSAIDs such as ibuprofen or aspirin might be useful. c) The other product of phospholipase A2 is a lysophospholipid (a lipid with a head group and only one fatty acid tail). These look a lot like detergents (i.e., SDS) and they are really good at solubilizing things such as membrane vescicles.41. Lipids as signals, cofactors, and pigments

Front 46

Describe the differences between the glycosphingolipids corresponding to the A, B, and O human blood group antigens.

Back 46

The type O structure is found in all three glycosphingolipids. In both type A and type B, there is an added sugar; this sugar differs between type A and B.

Front 47

Explain the cause of hereditary diseases of sphingolipid metabolism, such as Tay-Sachs and Niemann-Pick diseases.

Back 47

These diseases are the result of mutations in the genes that code for enzymes of sphingolipid breakdown. The mutant enzyme is defective and unable to catalyze its reaction in the metabolic pathway; this results in the accumulation of the metabolic intermediate that is the substrate for the enzyme. (See Box 10-1.)

Front 48

which vitamin is used for blood clotting

Back 48

k

Front 49

which vitamin is used for vision

Back 49

a

Front 50

which vitamin is used for ca2+ and phosphate metabolism

Back 50

d

Front 51

which vitamin is used for prevention of oxidative damage

Back 51

e

Front 52

Show the structure of isoprene; explain what is meant by isoprenoid compounds and give an example

Back 52

The structure is shown on page 17. Isoprenoid compounds contain chains that consist of multiple isoprene units. (See Fig. 10-22 for examples.)

Front 53

What do all these compounds have in common: vitamin A, vitamin K, ubiquinone, and dolichol?

Back 53

They are all lipids with potent biological activities derived from isoprenoid precursors.

Front 54

Explain why extraction of lipids from tissues requires organic solvents.

Back 54

: Lipids are either strongly hydrophobic or amphipathic. Because the solvent in tissues is water, lipids are mainly present in aggregates. This aggregation does not occur in organic solvents; as a result, the lipids are more soluble and thus extractable from the tissues.

Front 55

If beeswax, cholesterol, and phosphatidylglycerol were dissolved in chloroform, then subjected to thin-layer chromatography on silica gel using a mixture of chloroform/methanol/water as the developing solvent, which would move fastest?

Back 55

(phosphatidylglycerol, which has a negative charge on its head group) moves the slowest. (See Fig. 10-25.)