Deck 11: Lipids and Membranes

Question 1

Fatty acid groups are referred to as ________ groups.

A) Acetyl
B) Acyl
C) Prenyl
D) Isoprenoid
E) Isopentenyl

Answer 1

B

Question 2

The double bonds in naturally occurring fatty acids are usually _______ isomers.

A) Cis
B) Trans
C) Both cis and trans
D) Essential
E) Nonessential

Answer 2

A

Question 3

The essential fatty acids are

A) Arachidonic acid
B) Linoleic acid
C) Linolenic acid
D) Both A and B are correct
E) Both B and C are correct

Answer 3

E

Question 4

Fatty acids react with alcohols to form _____.

A) Amides
B) Ethers
C) Anhydrides
D) Epoxides
E) Esters

Question 5

Prostaglandins are involved in _________.

A) Ovulation
B) Inflammation
C) Digestion
D) Both A and B are correct
E) All of the above are correct

Question 6

The functions of fat include

A) Insulation
B) Energy storage
C) Water-repellent properties
D) Both A and B are correct
E) All of the above are correct

Question 7

Waxes

A) Are complex mixtures of nonpolar lipids
B) Are esters formed from long-chain fatty acids and long-chain alcohols
C) Contain hydrocarbons, sterols, and alcohols
D) Both A and B are correct
E) Both A and C are correct

Question 8

Phospholipids are

A) Structural components of membranes
B) Surface active agents
C) Rich energy sources
D) Both A and B are correct
E) All of the above are correct

Question 9

Phosphatidylcholine is sometimes referred to as ______.

A) PIP₂
B) Cephalin
C) Ceramide
D) Cardiolipin
E) None of the above is correct

Question 10

The myelin sheath

A) Surrounds nerve cell axons
B) Contains large amounts of cardiolipin
C) Facilitates nerve impulse transmission
D) Both A and B are correct
E) Both A and C are correct

Question 11

All of the following are glycolipids except _________.

A) Sulfatides
B) Cerebrosides
C) Gangliosides
D) Both A and B are correct
E) None of the above is correct

Question 12

The role of very low density lipoproteins is

A) Scavenging the cholesterol from cell membranes
B) Transporting of lipids from liver to tissues
C) Transporting of cholesterol esters to the liver
D) Both A and B are correct
E) All of the above are correct

Question 13

Which of the following statements concerning carotenoids is not true?

A) Carotenoids are the only examples of the monoterpenes
B) The carotenes are hydrocarbon members of the carotenoids
C) Xanthophylls are oxygenated derivatives of the carotenes
D) Carotenoids are orange-colored pigments
E) None of the above is true

Question 14

Which of the following molecules is not a lipid?

A) Fatty acids
B) Steroids
C) Isoprenoids
D) Waxes
E) All of the above are lipids

Question 15

The basic structure of biological membranes is a consequence of the physical properties of _______.

A) Proteins
B) Phospholipids
C) Cholesterol
D) Water
E) None of the above is correct

Question 16

A membrane's fluidity is largely determined by the percentage of

A) Phosphatidylcholine
B) Phosphatidylethanolamine
C) Wax esters
D) Cardiolipin
E) Unsaturated fatty acids

Question 17

In the fluid mosaic model of membrane structure

A) Proteins form an inner layer between two layers of lipid
B) Proteins coat an inner layer of lipids
C) Proteins float in a lipid bilayer
D) Proteins are covalently bonded to the lipid bilayer
E) All of the above are true

Question 18

Which of the following statements concerning the anion channel protein is not true?

A) It plays an important role in carbon dioxide transport in blood
B) It facilitates the chloride shift
C) Bicarbonate and chloride exchange occurs through the anion channel protein
D) The N-terminal methionine residue of the anion channel protein is prenylated
E) All of the above statements are true.

Question 19

Energy requiring transport mechanisms include

A) Primary active transport
B) Diffusion
C) Facilitated diffusion
D) Both A and B are correct
E) Both A and C are correct

Question 20

In simple diffusion a solute

A) Is propelled by random molecular motion
B) Moves up its concentration gradient
C) Moves across a membrane because of an input of free energy.
D) Both A and B are correct
E) All of the above are correct

Question 21

Which of the following statements is not true?

A) Membrane potential is an electrical gradient across a membrane.
B) A decrease in membrane potential is referred to as membrane depolarization.
C) The term repolarization is defined as the reestablishment of the original membrane potential.
D) The diffusion of potassium ions out of a nerve cell make the inside of the membrane negative.
E) The sodium channel in muscle and nerve cells is a voltage-gated channel.

Question 22

In muscle cells, local depolarization caused by acetylcholine binding leads to the opening of the voltage gated _____channels.

A) Chloride
B) Potassium
C) Proton
D) Sodium
E) Glucose permease

Question 23

The function of glucose permease is an example of

A) Primary active transport
B) Secondary active transport
C) Facilitated diffusion
D) Simple diffusion
E) None of the above is true

Question 24

$\omega$ -6 Fatty acids

A) Have a double bond six carbon atoms from the carbonyl end of the chain
B) Have a double bond six carbon atoms from the methyl end of the chain
C) Have six double bonds in the molecule
D) Have three more double bonds than $\omega$ -3 fatty acids
E) Contain six trans double bonds in the molecule

Question 25

Membrane receptors are transmembrane molecules or membrane molecular complexes that

A) Monitor and respond to changes in the cell's environment.
B) Bind to hormones or neurotransmitters
C) Are involved in embryonic and fetal development
D) Initiate an intracellular response when they bind an appropriate molecule
E) All of the above are correct

Question 26

Patients with familial hypercholesterolemia

A) Possess depressed levels of plasma cholesterol
B) Have missing or defective LDL receptors
C) Are homozygous or heterozygous for a nonfunctional LDL receptor gene
D) Have very high levels of serum cholesterol
E) B, C, and D are correct

Question 27

Indicate which of the following compounds is an endocannabinoid.

A) Oleic acid
B) Arachidonic acid
C) Anandamide
D) Prostaglandin
E) $\omega$ -3 Fatty acids

Question 28

Low fat diets deficient in essential fatty acids are characterized by which of the following?

A) Poor wound healing
B) Alopecia
C) Dental caries
D) Ketone bodies
E) Both A and B are correct

Question 29

Which of the following structural features is not characteristic of TXA₂?

A) An ether ring
B) One OH group
C) Two double bonds
D) One double bond
E) Is derived from arachidonic acid

Question 30

Neutral fats belong to which of the following?

A) Phospholipids
B) Glycolipids
C) Prostaglandins
D) Triacylglycerols
E) Free fatty acids

Question 31

In addition to the prostaglandins and leukotrienes the autocrine regulators include:

A) Arachidonic acid
B) Linoleic acid
C) Thromboxanes
D) Steroids
E) All of the above are correct

Question 32

Choose the lipid class that acts as surfactants.

A) Triacylglycerols
B) Fatty acids
C) Waxes
D) Phospholipids
E) Both A and B are correct

Question 33

Peripheral membrane proteins are linked to anchor molecules through a ___________ link

A) Ether
B) Ester
C) Amide
D) Amino
E) Plasma

Question 34

Glycolipids differ from sphingolipids in that they contain no _________.

A) Carbohydrate
B) Phosphate
C) Fatty acid
D) Choline
E) Both B and C are correct

Question 35

Which of the following is not likely to be a naturally occurring fatty acid?

A) C₁₃H₂₇COOH
B) C₁₄H₂₉COOH
C) C₁₅H₃₁COOH
D) C₁₇H₃₅COOH
E) C₁₉H₃₉COOH

Question 36

The function of dolichols is to

A) Transport sugars in glycoprotein synthesis
B) Bind carbohydrate on the cell surface of bacteria
C) Bind to oxygenated carotenes
D) Serve as precursors of carotenoids
E) They are degradation products of steroids

Question 37

Plasma lipoproteins transport _______ through the blood from one organ to another.

A) Triacylglycerols
B) Phospholipids
C) Cholesteryl esters
D) Both A and C are correct
E) All of the above are correct

Question 38

_________ are the principal transporters of cholesteryl esters to tissues.

A) Chylomicrons
B) Very low density lipoprotein
C) Intermediate density lipoprotein
D) Low density lipoprotein
E) All of the above are true

Question 39

Individuals with cystic fibrosis have a defective _______ ion channel in their epithelial membrane

A) Water
B) Chloride
C) Potassium
D) Protein
E) Sodium

Question 40

A consequence of replacing dietary fat content with sugars is

A) No effect on body weight
B) An increase in body weight
C) A small loss of body weight
D) A large decrease in body weight
E) An initial loss of weight followed by a large increase in body weight

Question 41

Which of the following is not a consequence of a low fat diet?

A) Low levels of fat soluble vitamins
B) Low levels of essential fatty acids
C) Brittle hair
D) Poor would healing
E) Low blood pressure

Question 42

Phospholipase B hydrolyzes ______ ester bonds in phospholipids

A) C-1
B) C-2
C) C-3
D) Both C-1 and C-2
E) All of the above

Question 43

Which of the following is not a function of phospholipases?

A) Membrane remodeling
B) Signal transduction
C) Energy storage
D) Digestion
E) Toxicity

Question 44

Membranes become more rigid when they contain

A) Large amounts of glycolipids
B) Large amounts of unsaturated fatty acids
C) Large amounts of saturated fatty acids
D) Large amounts of water
E) Both A and B are correct

Question 45

Flippase transfers _________ from the outer to inner membrane leaflet

A) Phospholipids
B) Cholesterol
C) Triacylglycerols
D) Glycolipids
E) Water

Question 46

What does the word saturated mean in the term saturated fatty acid?

Question 47

Where is the first carbon-carbon double bond in an $\omega$ -3 fatty acid?

Question 48

What is the major function of waxes?

Question 49

What is the major function of cholesterol?

Question 50

Why do plasma lipoproteins require a protein component to accomplish their role?

Question 51

What role do bile salts play in the body?

Question 52

What do the abbreviations ACAT and LCAT stand for? What functions do these molecules serve in lipid metabolism?

Question 53

From what fatty acids are most eicosanoids derived? What is the medical importance of eicosanoids? Provide an example.

Question 54

What is the difference between an autocrine regulator and a hormone?

Question 55

How do water molecules move through hydrophobic cell membranes?

Question 56

To which class of terpenes does the following molecule belong?

Question 57

How does the function of HDL promote the reduction of risk for coronary artery disease?

Question 58

What change would you make in the structure of a cell membrane to increase the cell's resistance to mechanical stress?

Question 59

List three mediator proteins that move phospholipid molecules from one side of a membrane to the other. What are the functions of each?

Question 60

Describe how glucose is transported across membranes in the kidney. What type of transport is involved?

Question 61

Describe and give specific examples of a facilitated diffusion process.

Question 62

Describe the general structure of lipoproteins. How does this structure allow the transport of water-insoluble lipid molecules in the bloodstream?

Question 63

Suggest a reason why elevated LDL levels are a risk factor for coronary artery disease.

Question 64

Mammals in the Arctic Circle (e.g., reindeer) have higher levels of unsaturated fatty acids in their legs than in the rest of their bodies. Suggest a reason for this phenomena. Does it have a survival advantage?

Question 65

Plants often produce waxes on the surface of their leaves to prevent dehydration and protect against insects. What structural feature of waxes makes them more suitable for this task than carbohydrates or proteins?

Question 66

Describe the possible consequences of a low fat diet.

Question 67

Explain why the bilayer translocation movement of phospholipids in cell membranes is relatively slow.

Question 68

Suggest a reason why trans fatty acids have melting points similar to analogous saturated fatty acids.

Question 69

Describe what cellular processes lipid rafts are involved in.

Question 70

Changes in temperature affect membrane properties. How would you expect the lipid composition of thermophile membranes to differ from those of prokaryotes that live at more normal temperatures?

Question 71

Detergents are synthetic soap-like substances that researchers use to disrupt membranes and extract membrane proteins. Explain how this process works.

Question 72

Explain why triacylglycerols are not components of lipid bilayers.

Question 73

Explain why entropy increases when a lipid bilayer forms from phospholipid molecules.

Question 74

Animal cells are enclosed in a cell membrane. According to the fluid mosaic model this membrane is held together by hydrophobic interactions. Considering the shear forces involved why does this membrane not break from shear stress.

Question 75

Glycolipids are nonionic lipids that can orient themselves into bilayers as phospholipids do. They accomplish this feat although they lack an ionic group like that of the phospholipids. Suggest a reason why this is possible.