Lipids and Proteins are Associated in Biological Membranes

Question 1

What characteristic is most used to define lipids?
a. ionic charge
b. melting point
c. solubility
d. ability to bind metal ions

Answer 1

c

Question 2

Which of the following lipid molecules possess a different fundamental structural make-up from the others?
a. Fatty acids
b. Cholesterol
c. Triglycerides
d. Sphingolipids
e. Glycolipids

Answer 2

b

Question 3

What does amphipathic mean?
a. having both positive and negative charges
b. having both acid and base properties
c. having both hydrophilic and hydrophobic regions
d. having two stereoisomers

Answer 3

c

Question 4

Which of the following statements is true?
a. All triacylglycerols and all phosphoacylglycerols have the same fatty acids in them.
b. All triacylglycerols have the same fatty acids, but the fatty acids in phosphoacylglycerols vary.
c. The fatty acids in triacylglycerols vary, but all phosphoacylglycerols have the same fatty acids in them.
d. The fatty acids in both triacylglycerols and in phosphoacylglycerols vary.

Answer 4

d

Question 5

How many hydroxyl groups does a molecule of glycerol have?
a. none
b. 1
c. 2
d. 3
e. 4

Answer 5

d

Question 6

Which of the following is true?
a. All fatty acids have an even number of carbons
b. Most fatty acids have an odd number of carbons
c. Fatty acids are equally likely to have an even number of carbons as they are an odd number
d. Fatty acids with an odd number of carbons are more rare than those with an even number
e. none of these

Answer 6

d

Question 7

Which of the following is not a characteristic of most fatty acids?
a. Presence of trans double bonds.
b. Even number of carbon atoms.
c. Only one carboxyl (−COOH) group.
d. Absence of conjugated double bonds.
e. All of these characterize lipids.

Answer 7

a

Question 8

Unsaturated fatty acids usually have ____ double bonds.
a. cis
b. trans
c. no
d. seven or eight

Answer 8

a

Question 9

Which of the following compounds yields the most energy per gram?
a. triacylglycerols
b. carbohydrates
c. proteins
d. They all yield about the same amount of energy per gram.

Answer 9

a

Question 10

What kinds of bonds do lipase break in order to release fatty acids from triacylglycerols?
a. esters
b. carbon-carbon single bonds
c. carbon-carbon double bonds
d. There are no fatty acids in triacylglycerols to release.

Answer 10

a

Question 11

Which of the following groups is not present in a phosphatidic acid?
a. Choline
b. Fatty acids
c. Glycerol
d. Phosphate
e. All of these are components of phosphatidic acid.

Answer 11

a

Question 12

Which of the following groups is not present in a cerebroside?
a. Sphingosine
b. Fatty acid
c. Phosphate
d. Sugar
e. All of these can be components of cerebrosides.

Answer 12

c

Question 13

Which of the following is not a product of saponification of a triglyceride?
a. Long chain fatty alcohols.
b. The salt of the fatty acids.
c. Soaps.
d. Glycerol.
e. All of these are products of saponification.

Answer 13

a

Question 14

Saponification is the hydrolysis of a(n)
a. peptide bond
b. ester bond
c. anhydride bond
d. glycosidic bond

Answer 14

b

Question 15

Which of the following groups is not present in lecithin?
a. Choline
b. Fatty acids
c. Glycerol
d. Phosphate
e. All of these are components of lecithin.

Answer 15

e

Question 16

Which of the following alcohols is never found in phosphatides?
a. Ethanolamine
b. Serine
c. Inositol
d. Sugars
e. All of these can be components of phosphatides.

Answer 16

e

Question 17

Which of the following lipids is not found in biological membranes?
a. triacylglycerols
b. phosphoacylglycerols
c. glycolipids
d. cholesterol

Answer 17

a

Question 18

Glycolipids are characterized by containing the following non-lipid component:
a. Sugars
b. Glycerol
c. Phosphate
d. Sphingosine
e. More than one of these characterize glycolipids.

Answer 18

a

Question 19

Phospholipids are particularly important in these structures:
a. Membranes.
b. Lipoproteins.
c. The brain and nervous system.
d. Membranes, the brain and the nervous system.
e. All of these are correct.

Answer 19

e

Question 20

Which of the following molecules is not amphipathic?
a. cholesterol
b. glucose
c. oleic acid
d. phosphatidylcholine

Answer 20

b

Question 21

Which of the following is true?
a. Fatty acids with trans double bonds may be particularly unhealthy because they increase the ratio of LDLs to HDLs.
b. A fatty acid with 14 carbons and one trans double bond will behave more like a saturated fatty acid with 14 carbons than will an unsaturated fatty acid with a cis double bond.
c. Fatty acids with trans double bonds can be formed by hydrogenation reaction of polyunssaturated fatty acids
d. fatty acids with trans double bonds tend to have higher melting points than those with cis double bonds all else being equal
e. All of these are correct

Answer 21

e

Question 22

Glycolipids are particularly important in these structures:
a. Membranes.
b. Lipoproteins.
c. The brain and nervous system.
d. Membranes, the brain and the nervous system.
e. All of these are correct.

Answer 22

d

Question 23

Sphingolipids are particularly important in these structures:
a. Membranes
b. Lipoproteins
c. The brain and nervous system.
d. Membranes, the brain and the nervous system.
e. All of these are correct.

Answer 23

d

Question 24

Which of the following groups is not present in sphingomyelin?
a. Sphingosine
b. Fatty acid
c. Phosphate
d. Sugar

Answer 24

d

Question 25

Which of the following four fatty acids has the highest melting point? a. CH3CH2CH2CH2CH2COOH b. CH3CH2CH2CH2CH2CH2CH2CH2CH2COOH c. CH3CH2CH2CH2CH2CH2CH2COH d. CH3CH=CHCH2CH2COOH

Answer 25

b

Question 26

The HDL class of lipoprotein is generally believed to be preventative of heart disease. a. True b. False

Answer 26

a

Question 27

Fatty acids with multiple double bonds are usually conjugated. a. True b. False

Answer 27

b

Question 28

Which of the following four fatty acids has the lowest melting point? a.) CH3CH2CH2CH2CH2COOH b.) CH3CH2CH2CH2CH2CH2CH2CH2CH2COOH c.) CH3CH2CH2CH2CH2CH2CH2COOH d.) CH3CH=CHCH2CH2COOH

Answer 28

d

Question 29

With what compound are fatty acids reacted to make a fat or oil? a. cholesterol b. glycerol c. sphinganine d. ceramide

Answer 29

b

Question 30

The myelin sheaths of neurons typically contain large amounts of a. waxes b. triacylglycerols c. cholesterol d. sphingolipids

Answer 30

d

Question 31

Lipids differ from most other biomolecules because they are defined on the basis of solubility, rather than on their chemical structure. a. True b. False

Answer 31

a

Question 32

Which of the following best describes lipids' insolubility in water? a. They are typically very soluble. b. They are typically insoluble. c. There is no general trend as to lipids' solubility in water.

Answer 32

b

Question 33

Glycolipids on the surface of cells are especially important as cell markers. a. True b. False

Answer 33

a

Question 34

Biological waxes are composed of a. glycerol and only one fatty acid. b. glycerol and two fatty acids c. a fatty acid and a long-chain alcohol. d. cholesterol and a fatty acid.

Answer 34

c

Question 35

Which of the following cell types contains cholesterol? a. bacteria b. animal c. plant d. They all contain cholesterol.

Answer 35

b

Question 36

Cholesterol is particularly important as a component of animal membranes. a. True b. False

Answer 36

a

Question 37

Membrane lipids in a lipid bilayer are held together by a. hydrophobic interactions b. hydrogen bonds c. electrostatic forces d. covalent bonds

Answer 37

a

Question 38

Cell membranes typically display asymmetry. What does this mean? a. The two leaves of a bilayer contain different collections of lipids and proteins. b. The fatty acyl chain on C-1 of a membrane lipid is usually different from that on C-3. c. Only one stereoisomer is ever seen at the chiral C-2 of the glycerol residue in a membrane lipid. d. Membrane lipids only have cis double bonds, never trans.

Answer 38

a

Question 39

How does the presence of cis double bonds in fatty acids affect membrane fluidity? a. They tend to increase the fluidity. b. They tend to decrease the fluidity. c. They don't have any specific effect on fluidity. d. fatty acids don’t have cis double bonds

Answer 39

a

Question 40

How does cholesterol affect membrane fluidity? a. It tends to increase the fluidity. b. It tends to decrease the fluidity. c. It doesn't have any specific effect on fluidity. d. membranes don’t have cholesterol

Answer 40

b

Question 41

Plants need cholesterol in their membranes to counteract the rigidity of the cell wall. a. True b. False

Answer 41

b

Question 42

Membranes are generally symmetrical, i.e., the outer face is composed of the same number and types of phospholipids as the inner face. a. True b. False

Answer 42

b

Question 43

Which of the following would not be enriched on the outer side of the lipid bilayer compared to the inner side? a. Phosphoacylglyerol b. Ganglioside c. Cerebroside d. Sphingomyelin

Answer 43

a

Question 44

The association of membrane proteins with lipids in the membrane bilayer always involves a. electrostatic interactions b. hydrophobic interactions c. covalent linkages d. all of the above

Answer 44

b

Question 45

The order-disorder transition (melting) in membranes a. is cooperative b. can be monitored by fluorescence techniques c. can be monitored by spin labeling d. all of these

Answer 45

d

Question 46

How do the membranes of plant and animal cells compare? a. Animal cell membranes tend to be more rigid than those of plant cells. b. Animal cell membranes tend to be more fluid than those of plant cells. c. Animal cell membranes tend to be more asymmetric than those of plant cells. d. Animal cell membranes tend to be more symmetric than those of plant cells

Answer 46

a

Question 47

Which of the following is not true? a. Plant oils are favored in the diet because they generally contain more unsaturated fats than found in animal fats. b. Unsaturated fatty acids are healthier for humans than saturated ones c. Heart disease can be correlated with diets high in saturated fatty acids d. Unsaturated fatty acids lead to higher levels of LDL than saturated fatty acids do

Answer 47

d

Question 48

The distribution of lipids in membranes is a. uneven, with bulkier molecules on the exterior b. characterized by even distribution of molecules c. distinguished by the absence of cholesterol d. not well understood

Answer 48

a

Question 49

The degree of membrane fluidity depends on a. the percentage of lipids that contain choline b. the percentage of glycolipids c. the percentage of fatty acids d. the percentage of unsaturated fatty acids

Answer 49

d

Question 50

Which of the following was not a desired goal of hydrogenating polyunsaturated fatty acids in butter-like spreads? a. To make the compound have the consistency of butter b. To make the compoound a solid at room temperature c. To put trans double bonds into the molecule d. To remove some of the double bonds in the molecule

Answer 50

c

Question 51

I find that briefly washing cells in a buffered solution at pH 11 is effective for isolating a cell membrane-associated hormone receptor. (A standard growth solution for the cells is pH 7.) Which of following best fits this description? a. This is an integral membrane protein that completely traverses the cell membrane. b. This is an integral membrane protein that only penetrates one leaf of the cell membrane. c. This is a peripheral membrane protein that probably interacts with membrane phospholipids using aspartatemediated salt bridges. d. This is a peripheral membrane protein that probably interacts with membrane phospholipids using lysine-mediated salt bridges.

Answer 51

d

Question 52

Which of the following is not a function or characteristic of membrane proteins? a. Transport b. Catalytic activity c. Blood clotting d. Receptor sites

Answer 52

c

Question 53

Where can membrane proteins be located? a. entirely within the membrane b. on the surface of the membrane c. in either position d. The position of membrane proteins has never been determined.

Answer 53

c

Question 54

When a membrane reaches its transition temperature, integral membrane proteins dissociate from the bilayer. a. True b. False

Answer 54

b

Question 55

Which property has not been observed for membrane proteins? a. being degraded for energy during biological pathways b. transport of substances into and out of the cell c. catalysis (enzymatic activity) d. acting as a receptor

Answer 55

a

Question 56

The freeze-fracture technique of electron microscopy is useful in studying membrane structure because a. integral membrane proteins can be seen in association with one leaflet of the lipid bilayer b. all the proteins can be removed from the membrane c. the degree of order of the lipid bilayer can be determined d. the presence of bound carbohydrates can be detected

Answer 56

a

Question 57

Which of the following treatments would be most useful in separating an integral membrane protein from the lipid component of a cell membrane? a. Change the pH. b. Add a salt. c. Add a detergent. d. Add a mixture of proteases. e. None of these. You can't separate an integral membrane protein from the lipid.

Answer 57

c

Question 58

Which of the following is the best phrase to describe the modern view of membrane structure? a. Membranes are lipid-lipid bilayers. b. Membranes are lipid-lipid bilayers with associated proteins. c. Membranes are composed solely of lipids and proteins. d. Membranes are a fluid mosaic of lipids and proteins. e. Membranes are found only in eukaryotic cells.

Answer 58

d

Question 59

Liposomes are a. artificial membrane-bounded structures used to deliver medications. b. single-layered membranes. c. mixed micelles involved in cholesterol transport among cells. d. bilayers with the hydrophobic regions on the outside.

Answer 59

a

Question 60

In the fluid mosaic model of membrane structure a. the proteins are specifically bonded to the lipids b. the proteins "float" in the lipid bilayer c. the proteins are sandwiched between the lipid molecules d. the lipids are sandwiched between the protein molecules

Answer 60

b

Question 61

Passive transport is the same as: a. simple diffusion b. facilitated diffusion c. active transport d. primary active transport

Answer 61

b

Question 62

The mechanism of membrane transport may involve the following: a. ATP hydrolysis. b. Conformation change of membrane proteins. c. Phosphorylation or dephosphorylation of membrane proteins. d. ATP hydrolysis and conformation change of membrane proteins. e. All of these are correct.

Answer 62

e

Question 63

The difference between active transport and passive transport is that a. concentration gradients are involved in one and not in the other. b. glycolipids play a role in one and not in the other. c. one requires expenditure of energy by the cell and the other does not. d. ions are transported into and out of the cell by one process and not by the other.

Answer 63

c

Question 64

Facilitated diffusion requires a. a channel protein through which the transported substance passes without binding b. a carrier protein to which the transported substance binds c. a receptor protein d. expenditure of energy by the cell

Answer 64

b

Question 65

Which of the following is not true? a. Receptors are often invaginated into the cell after binding to their specific molecule. b. A given receptor type is present at a constant level on the outside of a cell c. In certain disease states, the level of a given receptor is increased or decreased d. Binding of receptors to ligands sometimes shows hyperbolic binding curves

Answer 65

b

Question 66

In the operation of the sodium-potassium pump a. conformational changes in membrane proteins are inhibited b. the ions involved bind to the lipid portion of the membrane c. a membrane protein is phosphorylated with ATP as the source of the phosphate group d. a membrane protein is phosphorylated with ADP as the source of the phosphate group

Answer 66

c

Question 67

What distinguishes primary from secondary active transport? a. The requirement for protein. b. The type of linkage to ATP hydrolysis c. The number of kinds of molecules or ions transported d. The relative direction of transport

Answer 67

b

Question 68

Which of the following methods of transport across a membrane does not require a protein? a. Passive transport b. Facilitated transport c. Active Transport d. Simple diffusion e. they all require a protein

Answer 68

d

Question 69

Which of the following statements concerning active transport is true? a. It takes place in the same direction as a concentration gradient. b. It requires no expenditure of energy by the cell. c. It can be compared to water running downhill. d. A membrane-associate protein must be involved.

Answer 69

d

Question 70

A major difficulty in extracting receptor proteins from membranes is that a. it is difficult to remove the proteins from the membrane without denaturation b. there may be very few molecules of the protein in a cell c. receptor proteins tend to have high molecular weights d. all of these

Answer 70

d

Question 71

In the sodium-potassium pump a. sodium is transported out of the cell and potassium into the cell, both against concentration gradients b. sodium is transported into the cell and potassium out of the cell, both against concentration gradients c. sodium is transported out of the cell and potassium into the cell, both in the same direction as concentration gradients d. sodium and potassium are both transported out of the cell against concentration gradients

Answer 71

a

Question 72

A useful method for studying membrane proteins in place in the membrane is a. nuclear magnetic resonance b. x-ray crystallography c. treatment with mercaptoethanol d. treatment with detergents

Answer 72

a

Question 73

Glycoproteins on the cell surface are involved in this type of function: a. Cell identification b. Receptor sites c. Immune function d. Cell identification and receptor sites e. All of these are correct.

Answer 73

e

Question 74

The key reaction of eyesight (in dim light) involving vitamin A is: a. Reaction of the protein complex called Rhodopsin. b. A cis-trans isomerization of a double bond. c. Bleaching of a pigment in the retina. d. Reaction of Rhodopsin and cis-trans isomerization of a double bond. e. All of these.

Answer 74

e

Question 75

These two lipid vitamins are often found in membranes: a. A and D b. A and E c. D and E d. E and K e. None of these is the correct pair.

Answer 75

b

Question 76

The following lipid vitamin is often used to preserve foods from spoiling: a. A b. D c. E d. K e. None of these preserves food.

Answer 76

c

Question 77

Vitamin E has all of the following properties, except: a. It is an antioxidant. b. It can be made in the sunshine. c. It is essential for at least some mammal's fertility. d. It is often a component of membranes. e. All of these describe vitamin E.

Answer 77

b

Question 78

Rickets is caused by a deficiency in a. vitamin A. b. vitamin D. c. vitamin E. d. vitamin K.

Answer 78

b

Question 79

The vitamin needed for blood coagulation is a. vitamin A b. vitamin D c. vitamin E d. vitamin K

Answer 79

d

Question 80

The vitamin classified as fat soluble rather than water soluble is a. vitamin A b. vitamin B1 c. vitamin B6 d. vitamin C

Answer 80

a

Question 81

There are likely to be huge stores of lipid vitamins in healthy animals. a. True b. False

Answer 81

a

Question 82

Which of the following is not a lipid-soluble vitamin? a. Ascorbic Acid b. Cholicalciferol c. Vitamin K d. Retinol e. Tocopherol

Answer 82

a

Question 83

The following lipid vitamin has important involvement with calcium ions: a. A b. D c. E d. K e. More than one reacts with calcium ion.

Answer 83

e

Question 84

Which of the following is a metabolic precursor of prostaglandins & leukotrienes? a. vitamin A. b. arachidonic acid. c. sphingomyelin. d. cholesterol

Answer 84

b

Question 85

Aspirin produces most of its analgesic effects by a. binding to the plasma membrane of nerve cells b. inhibiting the synthesis of vitamin A c. inhibiting the synthesis of phospholipids d. inhibiting the synthesis of prostaglandins

Answer 85

d

Question 86

Which of the following does not belong in the list? a. Retinol b. Vitamin A c. beta-carotene d. Cholesterol

Answer 86

d

Question 87

Explain how the overall shape of fatty acids is affected by cis and trans double bonds.

Answer 87

The cis and trans double bonds contribute to the overall shape of the fatty acids. A cis double bond puts a kink in the long-chain hydrocarbon tail, whereas the shape of a trans fatty acid is like that of a saturated fatty acid in its fully extended conformation.

Question 88

When an organism uses fatty acids, the ester linkages of triacylglycerols are hydrolyzed by enzymes called _____. a. transferases b. lipases c. ligases d. isomerases

Answer 88

b

Question 89

Identify the type of lipids represented by the following structure. CH=CH(CH2)12CH3 | CHOH | O | || CHNHCR | O | || + CH2OPCH2CH2N(CH3)3 | O- a. Sphingolipids b. Glycolipids c. Triacylglycerols d. Phosphoacylglycerols | O

Answer 89

a

Question 90

Which of the following lipids is an example of glycolipids? a. Oleomargarine b. Progesterone c. Cholesterol d. Gangliosides

Answer 90

d

Question 91

Explain the significance of prostaglandins.

Answer 91

Prostaglandins control blood pressure, simulate smooth-muscle contraction, and induce inflammation. Prostaglandins are also known to inhibit the aggregation of platelets. They may thus be of therapeutic value by preventing the formation of blood clots, which can cut off the blood supply to the brain or the heart and cause certain types of strokes and heart attacks.