Final Exam Study Guide

E

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

B

Biological waxes are

A. Triesters of glycerol and palmatic 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

D

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

B. Gangliosides

C. Phosphatidyl serine

D. Platelet-activating factor

E. Sphingomyelin

B

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.

A

Which of the following is true of spingolipids?

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

E

Which of the following is not a glycerophospholipid?

A. Phosphatidylcholine

B. Phosphatodylethanolamine

C. Phosphatidylserine

D. Cardiolipin

E. Ceramide

B

Fatty acids are a component of:

A. Carotenes

B. Cerebrosides

C. Sterols

D. Vitamin D

E. Vitamin K

A

Which of the following statements abot 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

B

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

C

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)

B

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

A. A

B. C

C. D

D. E

E. K

E

Identify the molecule(s) derived from sterols.

A. Arachidonic acid

B. Gangliosides

C. Phosphatidylglycerol

D. Prostaglandins

E. Cortisol

D

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.

B

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

A

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 consitutent of sterols.

E. Fatty acids are strongly hydrophilic.

A

Sphingosine is not a component of:

A. Cardiolipin

B. Ceramide

C. Cerebrosides

D. Gangliosides

E. Sphingomyelin

D

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 (phosphatyidylcholine), 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

B

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

A. Cardiolipin

B. Ganglioside GM2

C. Phosphatyidylcholine

D. Platelet-activating factor

E. Sphingomyelin

B

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

B

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. Sterols are precursors of steroid hormones

E. Sterols have a structure that includes four fused rings.

A

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

A

Which of the following best describes the cholesterol molecule?

A. Amphipathic

B. Nonpolar, charged

C. Nonpolar, uncharged

D. Polar, charged

E. Polar, uncharged

C

Which vitamin is derived from cholesterol?

A. A

B. B12

C. D

D. E

E. K

C

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

Exergonic

Oxidation of fatty acids is highly exergonic or endergonic?

Chain length: # of bonds (Δ^{Position of double bonds})

Nomenclature for unbranched fatty acids

Polyunsaturated Fatty Acids (PUFAs)

Contain more than one double bond in their backbone

ALA (α-linolenic acid)

Humans must obtain ___ from their diet

EPA (eicosapentaenoic acid) & DHA (docosahexaenoid acid)

ALA is used to synthesis what two fatty acids?

Triacylglycerols

Composed of three fatty acids, each in ester linkage with a single glycerol

Nonpolar, hydrophobic

Triaglycerols are:

Nonpolar, hydrophobic

Polar, hydrophobic

Nonpolar, hydrophilic

Polar, hydrophilic

Increased

_________ chain length decreases solubility

Decreased

_________ double bond number decreases solubility

Saturated

At room temperature, _________ fatty acids have a waxy consistency

Unsaturated

At room temperature, ___________ fatty acids are oily liquids.

As lipid droplets in adipocytes

Where do vertebrates store triacylglycerols?

In the seeds

Where do plants store triacylglycerols?

Oxidation of fatty acids yields more energy & triacylglycerols are hydrophobic so they do not have to carry the extra weight of water

Why is it advantageous to use triacylglycerols as stored fuels?

Triacylglycerols

Warm-blooded polar animals are amply padded with _________________.

Partial Hydrogenation

Converts cis double bonds in fatty acids to single bonds

Increases

Partial hydrogenation _________ the melting temperature.

Bad

LDL is ___ cholesterol

Good

HDL is ____ cholesterol.

Biological Waxes

Ester sof long-chain saturated and unsaturated fatty acids with long-chain alcohols

Higher

Biological waxes have a ______ melting point than triacylglycerols

Glycerophospholipids

Membrane lipids in which two fatty acids are attached in ester linkage to the first and second carbons of glycerol, and a highly polar or charged group is attached through a phosphodiester linkage to the third carbon.

Phosphate

Attachment of what at one end of glycerol converts it to a chiral compound?

Ether Lipids

One of the two acyl chains is attached to glycerol in ether, rather than ester, linkage

Chain may be saturated

Sphingolipids

Large class of membrane phospholipids and glycolipids

Have a polar head group and two nonpolar tails

Contain no glycerol

Ceramide

Compound resulting when a fatty acid is attached in amide linkage to the -NH₂ on C-2

Parent compound of sphingolipids

Sphingomyelins

Subclass of sphingolipids that contains phosphocholine or phosphoethanolamine as their polar head group

Phosphate

Glycosphingolipids do not contain _________

Cerebrosides

Have a single sugar linked to ceramide

Globosides

Glycosphingolipids with 2+ sugars

Gangliosides

Have oligosaccharides as their polar head groups and 1+ residues of N-acetylneuraminic acid, a sialic acid, at the termini

Oligosaccharide

Human blood groups are determined in part by the _______________ head groups of glycosphingolipids

Phospholipases & lysophospholipases

What two lipases remove two fatty acids?

Eicosanoids

Paracrine hormones, substances that act only on cells near the point of hormone synthesis instead of being transported in the blood

Prostaglandins, thromboxanes, leukotrienes, and lipoxins

Four major classes of eicosanoids

Prostaglandins

Class of eicosanoids that contain a five-carbon ring

Prostaglandins

Class of eicosanoids that stimulate contraction of the smooth muscle of the uterus and affect blood flow

Thromboxanes

Class of eicosanoids that have a six-membered ring containing an ether and produced by platelets

Leukotrienes

Class of eicosanoids that contain three conjugated double bonds

Lipoxins

Class of eicosanoids that are linear and contain several hydroxyl groups along the chain

Potent anti-inflammatory agents

Steroids

Oxidized derivatives of sterols

Lack the alkyl chain attached to ring D of cholesterol

More polar than cholesterol

Vtiamin D3

Vitamin formed in the skin driven by the UV component of sunlight

Not biologically active

Vitamin D3

Deficiencies of this vitamin cause defective bone formation and the disease rickets

Vitamin A1

Vitamin that acts in processes of development, cell growth and differentiation, and vision

Vitamin A

Deficiencies of this vitamin cause congenital malformations and leads to dryness of skin, eyes, and mucous membranes, and night blindness

Vitamin E

Collective name for a group of lipids called tocopherols

Tocopherols

Hydrophobic compounds that contain a substituted aromatic ring and a long isoprenoid side chain

Vitamin E

Deficiencies of this vitamin cause scaly skin, muscular weakness and wasting, and sterility

Principal symptom is fragile erythrocytes

Vitamin K

Vitamin containing an aromatic ring

Essential in blood clotting

Warfarin

A synthetic compound that inhibits the formation of active prothrombin

Ubiquinone

Drives ATP Synthesis

Dolichols

Isopenoid alcohols that activate and anchor sugars to cellular membranes

Polyketides

Diverse group of lipids with Claisen condensations similar to those for fatty acids

Chloroform layer

Lipids remain in what layer after being extracted?

Methanol/water layer

Proteins and sugars remain in what layer after being extracted?

C

Which of these statements about the composition of membranes is true?

A. All biological membranes contain cholesterol

B. Free fatty acids are major components of all membranes

C. The inner and outer membranes of mitochondria have different protein compositions

D. The lipid composition of all membranes of eukaryotic cells is essentially the same

E. The lipid:protein ratio varies from about 1:4 to 4:1

A

Which of these statements about the composition of biological membranes is false?

A. In a given eukaryotic cell type (e.g. hepatocyte), all intracellular membranes have essentially the same complement of lipids and proteins

B. The carbohydrate found in membranes is virtually all part of either glycolipids or glycoproteins

C. The plasma membranes of the cells of vertebrate animals contain more cholesterol than the mitochondrial membranes.

D. The ratio of lipid to protein varies widely among cell types in a single organism.

E. Triacylglycerols are not commonly found in all membranes

B

The shortest α helix segment in a protein that will span a membrane bilayer has about ____ amino acid residues

A. 5

B. 20

C. 50

D. 100

E. 200

E

Membrane proteins:

A. are sometimes covalently attached to lipid molecules

B. are sometimes covalently attached to carbohydrate moieties

C. are composed of the same 20 amino acids found in soluble proteins

D. diffuse laterally in the membrane unless they are anchored

E. have all the properties listed above

E

A hydropathy plot is used to:

A. determine the water-solubility of a protein

B. deduce the quaternary structure of a membrane protein

C. determine the water content of a native protein

D. extrapolate for the true molecular weight of a membrane protein

E. predict whether a given protein sequence contains membrane-spanning segments

C

Which of the following are not enzymes involved in moving phospholipids from one leaflet to another?

A. Flippases that move phosphatidylethanolamine and phosphatidylserine

B. Floppases that move phospholipids from the cytosolic leaflet to the extracellular leaflet

C. Flip-floppases that allow phospholipids to move back and forth between the inner and outer leaflets

D. Scramblases that allow phospholipids to move down their concentration gradient

E. Phosphatidylinositol transfer proteins that play a role in lipid signaling

C

When a bacterium such as E. coli is shifted from a warmer growth temperature to a cooler growth temperature. It compensates by:

A. increasing its metabolic rate to generate more heat

B. putting longer-chain fatty acids into its membranes

C. putting more unsaturated fatty acids into its membranes

D. shifting from aerobic to anaerobic metabolism

E. synthesizing thicker membranes to insulate the cell

B

Which of the following statements about caveolin is false?

A. Caveolin is an integral membrane protein

B. Caveolin induces outward membrane curvature.

C. Caveolin is palmitoylated

D. Caveolin associates with cholesterol rich regions

E. Caveolin is involved in membrane trafficking and cellular signaling

C

A process not involving the fusion of two membranes or two regions of the same membrane is:

A. endocytosis

B. entry of enveloped viruses into cells

C. entry of glucose into cells

D. exocytosis

E. reproductive budding in yeast

C

Integrins are:

A. membrane proteins that are involved in ion transport

B. membrane proteins that are involved in sugar transport

C. membrane proteins that mediate cell adhesion

D. proteins of the extracellular matrix that bind to cell surface proteins

E. proteins that are found at the membrane-cytoplasm interface

A

Facilitated diffusion through a biological membrane is:

A. driven by a difference of solute concentration

B. driven by ATP

C. endergonic

D. generally irreversible

E. not specific with respect to the substrate

A

Which of these statements about facilitated diffusion across a mebrane is true?

A. A specific membrane protein lowers the activation energy for movement of the solute through the membrane

B. It can increase the size of a trnasmembrane concentration gradient of the diffusing solute

C. It is impeded by the solubility of the transported solute in the nonpolar interior of the lipid bilayer

D. It is responsible for the trnasport of gases such as O₂, N₂, and CH₄ across biological membranes

E. The rate is not saturable by the transported substrate

B

Consider the transport of glucose into an erythrocyte by facilitated diffusion. When the glucose concentrations are 5 mM on the outside and 0.1 mM on the inside, the free-energy change for glucose uptake into the cell is: (These values may be of use to you: R = 8.315 J/mol-K; T = 298 K; 9 (Faraday constant) = 96,480 J/V; N = 6.022 × 10²³ mol)

A. less than 2 kJ/mol

B. about 10 kJ/mol

C. about 30 kJ/mol

D. about -30 kJ/mol

E. impossible to calculate without knowledge of the membrane potential

D

The type of transport that uses ion gradients as the energy source is:
A. facilitated diffusion

B. passive transport

C. primary active transport

D. secondary active transport

E. simple diffusion

B

Movement of water across membranes is facilitated by proteins called:

A. annexins

B. aquaporins

C. hydropermeases

D. selectins

E. transportins

B

In one catalytic cycle, the Na⁺/K⁺ ATPase transporter transports:

A. 2 Na⁺ out, 3 K⁺ in, and converts 1 ATP to ADP + P_i

B. 3 Na⁺ out, 2 K⁺ in, and converts 1 ATP to ADP + P_i

C. 3 Na⁺ in, 2 K⁺ out, and converts 1 ATP to ADP + P_i

D.1 Na⁺ out, 1 K⁺ in, and converts 1 ATP to ADP + P_i

E. 2 Na⁺ out, 23K⁺ in, and converts 1 ADP + P_i to ATP

A

The specificity of the potassium channel for K⁺ over Na⁺ is mainly the result of the:

A. differential interaction with the selectivity filter protein

B. hydrophobicity of the channel

C. phospholipid composition of the channel

D. presence of carbohydrates in the channel

E. presence of cholesterol in the channel

A

The specificity of aquaporins for water is not ensured by which of the following?

A. The channel contains a negatively charged Asp residue to scavenge protons and H₃O⁺

B. The diameter of the channel narrows to 2.8 A

C. There are carbonyl backbone residues in the channel that hydrogen bond with water

D. Arg and His residues in the channel repel protons and H₃O⁺

^{E. Electric dipoles of short α-helices repel protons and} H₃O⁺

C

The inner (plasma) membrane of E. coli is about 75% lipid and 25% protein by weight. How many molecules of membrane lipid are there for each molecule of protein? (Assume that the average protein is M_r 50,000 and the average lipid is 750.)

A. 1

B. 50

C. 200

D. 10,000

E. 50,000

C

Which one of the following statements about membranes is true?

A. Most plasma membranes contain more than 70% proteins

B. Sterol lipids are common in bacterial plasma membranes

C. Sterol lipids are common in human cell plasma cells

D. Sterol lipids are common in plant cell plasma membranes

E. The plasma membranes of all cell types within a particular organism have basically the same lipid and protein composition

A

Peripheral membrane proteins:

A. are generally noncovalently bound to membrane lipids

B. are usually denatured when released from membranes

C. can be released from membranes only by treatment with detergent(s)

D. may have functional units on both sides of the membrane

E. penetrate deeply into the lipid bilayer