Deck 10: Lipids

Question 1

Which statement 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.

Answer 1

A

Question 2

Which statement 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.

Answer 2

B

Question 3

Nonsteroidal 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 answers is correct.

Answer 3

B

Question 4

Triacylglycerols are composed of:

A) a glycerol backbone.
B) three fatty acids.
C) amide linkages between the fatty acids and the glycerol.
D) both a glycerol backbone and three fatty acids.
E) a glycerol backbone, three fatty acids, and amide linkages between the fatty acids and the glycerol.

Question 5

Sphingosine is NOT a component of:

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

Question 6

Which statement 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 7

Which statement 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 8

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 9

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 answers is correct.

Question 10

Which statement 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.

Question 11

Which statement 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 12

Which compound is NOT a glycerophospholipid?

A) phosphatidylcholine
B) phosphatidylethanolamine
C) phosphatidylserine
D) cardiolipin
E) ceramide

Question 13

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 14

_____ contain(s) an ether-linked alkyl group.

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

Question 15

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

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

Question 16

Which term BEST describes the cholesterol molecule?

A) amphipathic
B) nonpolar, charged
C) nonpolar, uncharged
D) polar, charged
E) polar, uncharged

Question 17

Which factor 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 18

Which statement 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

Fatty acids are a component of:

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

Question 20

Which molecules or substances contain, or are derived from, fatty acids?

A) beeswax
B) prostaglandins
C) sphingolipids
D) triacylglycerols
E) All of these contain or are derived from fatty acids.

Question 21

Which health effect is NOT associated with consumption of trans fats?

A) lowering of HDL cholesterol
B) increased inflammatory response in the body
C) raising of LDL cholesterol
D) increased joint flexibility due to additional membrane fluidity
E) increased risk of heart disease

Question 22

Humans make which omega-3 polyunsaturated fatty acid from alpha-linolenic acid (ALA)?

A) eicosapentaenoic acid (EPA)
B) arachidonic acid (ARA)
C) docosahexaenoic acid (DHA)
D) both eicosapentaenoic acid (EPA) and arachidonic acid (ARA)
E) both eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)

Question 23

Identify the molecule(s) derived from sterols.

A) arachidonic acid
B) gangliosides
C) phosphatidylglycerol
D) prostaglandins
E) cortisol

Question 24

Which statement is TRUE about fatty acids?

A) Fatty acids with longer chains have higher melting points.
B) Fatty acids with longer chains have lower solubility in water.
C) Fatty acids with more double bonds have higher melting points.
D) Fatty acids with longer chains have higher melting points and lower solubility in water.
E) None of the statements is true.

Question 25

Which vitamin is NOT fat soluble?

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

Question 26

_____ is NOT a biological use of waxes.

A) Energy storage
B) Lubrication
C) Structure
D) Insulation
E) Waterproofing

Question 27

Waxes are BEST described as:

A) esters of glycerol and three fatty acids.
B) esters of one long-chain fatty acid and one long-chain alcohol.
C) polyunsaturated long-chain fatty acids.
D) esters of two long-chain fatty acids.
E) ethers of glycerol and short-chain alcohols.

Question 28

What is the abbreviated nomenclature for octadecanoic acid with two double bonds?

A) 16:1
B) 14:2
C) 18:2
D) 18:0
E) 18:1

Question 29

Which technique 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 30

Which type of chemical linkage is used to join fatty acids to glycerol?

A) an ether linkage
B) a peptide bond
C) an ester linkage
D) a double bond
E) a peroxide bond

Question 31

Which term BEST describes the polarity of membrane lipids?

A) ambidextrous
B) completely nonpolar
C) amphipathic
D) completely polar
E) amphibolic

Question 32

Which compound is NOT a type of membrane lipid?

A) sphingolipid
B) glycerophospholipid
C) sulfolipid
D) sterol
E) triacylglycerolipid

Question 33

Which vitamin is derived from cholesterol?

A) A
B) B₁₂
C) D
D) E
E) K

Question 34

Advantages to using triacylglycerols, rather than polysaccharaides, to store energy include which reason(s)?

A) The carbon atoms of triacylglycerols are more reduced.
B) Triacylglycerols contain more oxygen than polysaccharides and therefore are more efficient to oxidize.
C) Since triacylglycerols are hydrophobic, excess water does not need to be stored along with them.
D) The carbon atoms of triacylglycerols are more reduced, and since triacylglycerols are hydrophobic, excess water does not need to be stored along with them.
E) Triacylglycerols contain more oxygen than polysaccharides and therefore are more efficient to oxidize, and since triacylglycerols are hydrophobic, excess water does not need to be stored along with them.

Question 35

Which statement describes a distinct difference between membrane lipids in archaea and membrane lipids in eukarya?

A) Archaeal membrane lipids have alkyl acids that are ether-linked to glycerol at both ends.
B) Eukaryotic membrane lipids consist of glycerol that is ester-linked to three fatty acids.
C) Only eukaryotic membrane lipids are amphipathic.
D) Archaeal membrane lipids always contain sphingosine.
E) Eukaryotic membrane lipids always have a phosphate group attached to glycerol.

Question 36

Commercial vegetable oils can be converted from liquid forms to solid forms and have their shelf lives increased due to which process?

A) partial desaturation
B) unsaturation
C) partial hydrogenation
D) hydrolysis
E) complete esterification

Question 37

Human adipocytes contain which enzyme that catalyzes the breakdown of triacylglycerols?

A) glycerase
B) lipase
C) fatase
D) esterase
E) triacylase

Question 38

What is the abbreviated nomenclature for a 14-carbon omega-3 fatty acid that contains no other double bonds?

A) 14:1( $\Delta$ 11)
B) 17:1( $\Delta$ 14)
C) 14:1( $\Delta$ 3)
D) 13:1( $\Delta$ 11)
E) 14:0( $\Delta$ 11)

Question 39

Which molecule is MOST commonly used as a backbone the linkage of three fatty acids to form fats?

A) glycogen
B) glycerol
C) sphingosine
D) glucose
E) phosphoglycerol

Question 40

Which statement BEST describes why lipids typically float on water?

A) Lipids are nonpolar, while water is polar.
B) Lipids have lower specific gravities than water does.
C) Lipids have higher melting temperature than water does.
D) Lipids store more energy than water does.
E) Lipids contain carbon, while water does not.

Question 41

Platelet-activating factor is much more water soluble than most other glycerophospholipids due to which feature?

A) its ether-linked alkyl chain at the C-1 of glycerol
B) its ester-linked acetic acid at the C-2 of glycerol
C) its ethanolamine head group
D) its lack of any long alkyl chains linked to glycerol
E) the presence of sphingosine, rather than glycerol, as a lipid backbone

Question 42

The steroid hormones testosterone and beta-estradiol are derived from which lipid molecule?

A) phosphatidylcholine
B) cholesterol
C) lipoxin A
D) arachidonic acid
E) geraniol

Question 43

Which membrane lipid serves as a reservoir of messenger molecules for signal transduction?

A) taruocholic acid (TA)
B) phosphatidylserine (PS)
C) phosphatidylinositol 4,5-bisphosphate (PIP₂)
D) thromboxane A₂ (TXA₂)
E) sphingomyelin (SM)

Question 44

Which types of membrane lipids are modified to determine blood type in humans?

A) phosphatidylserines
B) glycosphingolipids
C) galactolipids
D) plasmalogens
E) sphingomyelins

Question 45

Which types of membrane lipids make up 70% to 80% of the total membrane lipids in a vascular plant?

A) phosphatidylserines
B) glycosphingolipids
C) galactolipids
D) plasmalogens
E) sphingomyelins

Question 46

Which compound can be cleaved in half to generate a molecule important in vision?

A) calcitol
B) beta-carotene
C) arachidonic acid
D) tocopherol
E) isoprene

Question 47

Which drug is NOT lipid based?

A) prednisone
B) warfarin
C) erythromycin
D) aspirin
E) lovastatin

Question 48

Nonsteroidal antiinflammatory drugs (NSAIDs) inhibit the synthesis of which signaling lipids from arachidonic acid?

A) prostaglandins
B) thromboxanes
C) leukotrienes
D) both prostaglandins and thromboxanes
E) both thromboxanes and leukotrienes

Question 49

You are working in a laboratory trying to design a drug that specifically binds to the surface of certain cells. To which membrane lipid constituents should your drug bind in order to achieve this specificity?

A) sphingomyelins
B) phosphatidylcholines
C) gangliosides
D) triacylglycerols
E) sterols

Question 50

If a patient you are treating has asthmatic attacks due to the overproduction of leukotrienes, which drug would you prescribe to help treat that condition?

A) testosterone
B) ibuprofen
C) aspirin
D) prednisone
E) warfarin

Question 51

What feature do Tay-Sachs disease, Fabry disease, and Niemann-Pick disease have in common?

A) defects in enzymes responsible for synthesizing membrane lipids
B) defects in enzymes responsible for breaking down membrane lipids in the lysosomes
C) hyperactive membrane lipid degradation enzymes
D) defects in enzymes responsible for cholesterol synthesis
E) All of the answers are correct.

Question 52

Which glycerophospholipid has a net charge of zero at pH 7?

A) phosphatidylserine
B) phasphatidic acid
C) phosphatidylcholine
D) phosphatidylglycerol
E) phosphatidylinositol 4,5-bisphosphate

Question 53

Bile acids are derived from which lipid?

A) cholesterol
B) sphingomyelin
C) ceramide
D) digalactosyldiacylglycerol
E) phosphatidylcholine

Question 54

Which feature allows certain lipid molecules to be used as colorful pigments in plants and animals?

A) Their high oxygen content helps electrons circulate, which allows absorption of visible light.
B) Their conjugated bond structures allow absorption of visible light.
C) Their four-fused ring structure allows visible light reflection.
D) Their hydrophobicity bends light around them.
E) Their low specific gravities cause light to reflect from their surfaces.

Question 55

Fatty acids are attached to sphingosine by what type of chemical linkage?

A) an ether linkage
B) an amide linkage
C) an ester linkage
D) a peroxide linkage
E) a alkyl linkage

Question 56

Which eicosanoids contains a five-carbon ring as part of its structure?

A) thromboxanes
B) prostaglandins
C) lipoxins
D) leukotrienes
E) arachidonates

Question 57

Which types of signaling lipids are produced by platelets to aid in the formation of blood clots?

A) prostaglandins
B) thromboxanes
C) arachidonates
D) lipoxins
E) leukotrienes

Question 58

A patient you are treating appears to be deficient in vitamin D. You have previously prescribed vitamin D supplements, but they do not appear to be working. Which organs and/or tissues should you check to make sure that the enzymes they produce are functioning appropriately?

A) the liver
B) the kidneys
C) the pancreas
D) both a the liver and the kidneys
E) the liver, the kidneys, and the pancreas

Question 59

Overproduction of which types of signaling lipids causes asthmatic attacks?

A) prostaglandins
B) thromboxanes
C) arachidonates
D) lipoxins
E) leukotrienes

Question 60

Which phospholipid head group is positively charged at pH 7?

A) serine
B) ethanolamine
C) choline
D) both serine and ethanolamine
E) both ethanolamine and choline

Question 61

If you wanted to analyze membrane lipids from a biological sample, which solvent would MOST effectively extract those lipids?

A) benzene
B) methanol
C) water
D) chloroform
E) ethyl ether

Question 62

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 63

The study and classification of the complete set of lipids produced in an organisms is called:

A) proteomics.
B) lipidomics.
C) genomics.
D) lipidification.
E) fatification.

Question 64

Which technique would you NOT use to separate and/or analyze lipids in a laboratory?

A) gel electrophoresis
B) thin-layer chromatography
C) adsorption chromatography
D) mass spectrometry
E) high-performance liquid chromatography (HPLC)

Question 65

When a tissue sample is homogenized in a extractant composed of chloroform, methanol, and water, followed by addition of more water to separate the liquid phases, which molecules will remain in the methanol/water phase?

A) lipids
B) proteins
C) sugars
D) both lipids and proteins
E) both proteins and sugars

Question 66

Which solvent is a commonly used to extract all the lipids from homogenized tissue samples and subsequent separation of the lipids from the proteins and sugars present in those samples?

A) ethanol
B) benzene
C) a mixture of chloroform, methanol, and water
D) water
E) a mixture of chloroform and benzene

Question 67

Which types of lipids would NOT have their fatty acids completely hydrolyzed by treatment with acid or alkali?

A) triacylglycerols
B) galactolipids
C) sphingomyelins
D) plasmalogens
E) phosphatidylcholines

Question 68

Which statement BEST describes how the volatility of lipids is increased for analysis by gas chromatography?

A) The lipids are transesterified to convert fatty acids into fatty acid methyl esters.
B) The lipids are cleaved with phospholipase enzymes .
C) The lipids are degraded by treatment with mild acid or base.
D) The lipids are dissolved in chloroform.
E) The lipids are desaturated by reaction with a platinum catalyst.

Question 69

Which technique separates lipids based on their affinity for a silica gel material?

A) thin-layer chromatography
B) adsorption chromatography
C) mass spectrometry
D) both thin-layer and absorption chromatography
E) both thin-layer chromatography and mass spectrometry

Question 70

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 71

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

Question 72

Phospholipase C hydrolyzes phosphatidylinositol 4,5-bisphosphate (PIP₂) to form which signaling molecule that triggers Ca²⁺ release from the endoplasmic reticulum?

A) diacylglycerolphosphate (DAGP)
B) inositol 5-monophosphate (IP₁)
C) diacylglycerol (DAG)
D) inositol 1,4,5-triphosphate (IP₃)
E) inositol 4,5-bisphosphate (IP₂)

Question 73

Specific hydrolysis of phosphatidylcholine can be achieved by which technique?

A) treatment of the lipid with phospholipase C
B) treatment of the lipid with mild acid
C) dissolving the lipid in chloroform
D) treatment of the lipid with both phospholipase C and mild acid
E) both treatment of the lipid with phospholipase C and dissolving the lipid in chloroform

Question 74

Which method can be used to visualize lipids that have been separated by thin-layer chromatography by reversibly reacting with double bonds in fatty acids?

A) ethanol
B) iodine fumes
C) low-wavelength UV light
D) rhodamine
E) ethidium bromide

Question 75

Which technique used to analyze lipids is the fastest but may not be the most accurate?

A) thin-layer chromatography
B) high-performance chromatography
C) nuclear magnetic resonance
D) direct mass spectrometry
E) gas chromatography

Question 76

Which solvent is NOT used to dissolve lipids?

A) ethyl ether
B) water
C) benzene
D) methanol
E) chloroform

Question 77

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

Question 78

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 79

In high-performance liquid chromatography of lipid mixtures using a column packed with a silica gel, which types of lipids will elute first?

A) positively charged lipids
B) neutral lipids
C) negatively charged lipids
D) polar lipids
E) zwitterionic lipids

Question 80

Which lipid compound is NOT at least partially made from the condensation of isoprene units?

A) sterols
B) limonene
C) beta-carotene
D) vitamin E
E) phosphatidylinositol