Deck 10: Lipids

Question 1

Which of the following contains an ether-linked alkyl group?

A)Cerebrosides
B)Gangliosides
C)Phosphatidyl serine
D)Platelet-activating factor
E)Sphingomyelin

Answer 1

Platelet-activating factor

Question 2

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.

Answer 2

A fatty acid is the precursor of prostaglandins.

Question 3

A compound containing N-acetylneuraminic acid (sialic acid)is:

A)cardiolipin.
B)ganglioside GM2.
C)phosphatidylcholine.
D)platelet-activating factor.
E)sphingomyelin.

Answer 3

ganglioside GM2.

Question 4

Which of the following is not a glycerophospholipid?

A)Phosphatidylcholine
B)Phosphatidylethanolamine
C)Phosphatidylserine
D)Cardiolipin
E)Ceramide

Question 5

Which of the following best describes the cholesterol molecule?

A)Amphipathic
B)Nonpolar,charged
C)Nonpolar,uncharged
D)Polar,charged
E)Polar,uncharged

Question 6

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.

Question 7

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.

Question 8

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.

Question 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.

Question 10

Non-steroidal anti-inflammatory drugs (NSAIDS)like aspirin and ibuprofen act by blocking production of:

A)biological waxes
B)prostaglandins
C)sphingolipids
D)vitamin D
E)none of the above

Question 11

Which of the following is not a consequence of partial hydrogenation of vegetable oils?

A)Longer shelf life
B)Lower melting temperature
C)Reduction of some cis double bonds to single bonds
D)Conversion of some cis double bonds to trans double bonds
E)Increased risk of cardiovascular disease upon consumption by humans

Question 12

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.

Question 13

Fatty acids are a component of:

A)carotenes.
B)cerebrosides.
C)sterols.
D)vitamin D.
E)vitamin K.

Question 14

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.

Question 15

Sphingosine is not a component of:

A)cardiolipin.
B)ceramide.
C)cerebrosides.
D)gangliosides.
E)sphingomyelin.

Question 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.

Question 17

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.

Question 18

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.

Question 19

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

Question 20

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).

Question 21

Circle the fatty acid in each pair that has the higher melting temperature.
(a)18:1 ^{$\Delta$ 9} 18:2 ^{$\Delta$ 9,12}
(b)18:0 18:1 ^{$\Delta$ 9}
(c)18:0 16:0

Question 22

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?

Question 23

Show the basic structure of all glycerophospholipids.

Question 24

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

Question 25

Identify the molecule(s)derived from sterols.

A)Arachidonic acid
B)Gangliosides
C)Phosphatidylglycerol
D)Prostaglandins
E)Cortisol

Question 26

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

Question 27

Which of the following is not a fat-soluble vitamin?

A)A
B)C
C)D
D)E
E)K

Question 28

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.

Question 29

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

Question 30

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

Question 31

Which vitamin is derived from cholesterol?

A)A
B)B₁₂
C)D
D)E
E)K

Question 32

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

Question 33

What chemical features distinguish a plasmalogen from a common glycerophospholipid?

Question 34

In cells,fatty acids are stored as triacylglycerols for energy reserves.
(a)What is the molecule to which fatty acids are esterified to form triacylglycerols? (b)Define the logic behind cells storing fatty acids in esterified form.

Question 35

What chemical features distinguish a cerebroside from a ganglioside?

Question 36

Which of the following techniques is not commonly used to analyze lipid composition?

A)Selective extraction using apolar solvents
B)Adsorption chromatography
C)X-ray crystallography
D)Hydrolysis using enzymes with specificity for certain linkages
E)Mass spectroscopy

Question 37

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

Question 38

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

Question 39

Match the compounds on the left with the important roles they play listed on the right.(Answers are used only once. )
(a)prostaglandins ___ blood clotting
(b)vitamin E ___ intra-tissue messengers
(c)sphingolipids ___ necessary for sight
(d)thromboxanes ___ mediates pain and inflammation
(e)vitamin A ___ important component of myelin membranes
(f)steroids ___ reducing agent

Question 40

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

Question 41

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

Question 43

Match each of these vitamins with its biological role: Vitamins A,D,E,K.
____ blood clotting
____ vision
____ Ca²⁺ and phosphate metabolism
____ prevention of oxidative damage

Question 44

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

Question 46

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?

Question 47

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

Question 48

Explain why extraction of lipids from tissues requires organic solvents.