Lipids

Question 1

Lipids may be either hydrophobic or ________.
a. Hydrophilic
b. Organic
c. Inorganic
d. Amphipathic
e. Soluble in polar solvents

Answer 1

d. Amphipathic

Question 2

_____ are the simplest lipids but they may be a part of or a source of many complex lipids.
a. Triglycerols
b. Carbohydrates
c. Terpenes
d. Fatty acids
e. Waxes

Answer 2

d. Fatty acids

Question 3

Isoprenoids are lipids, which do not contain, nor are derived from, fatty acids and include ______.
a. Steroids
b. Waxes
c. Terpenes
d. a and c
e. a, b, and c

Answer 3

d. a and c

Question 4

A fatty acid designated as 20:0 is ________, while one that is designated 20:35,8,11 is _______.
a. Simple; complex
b. Complex; simple
c. Saturated; unsaturated
d. Unsaturated; saturated
e. Monounsaturated; polyunsaturate

Answer 4

c. Saturated; unsaturated

Question 5

A sea creature richer in __________ can more likely live or migrate to an area of low temperature.
a. Arachidonic acid
b. All fatty acids
c. unsaturated fatty acids
d. Eicosanoids
e. All of the above

Answer 5

c. unsaturated fatty acids

Question 6

Fatty acids required in the diet of mammals are called ______.
a. Important lipids
b. Dietary lipids
c. Saturated lipids
d. Essential lipids
e. Esters

Answer 6

d. Essential lipids

Question 7

Dietary triacylglycerols are digested as a result of ________.
a. Lipase action
b. Bile salts
c. Micelle formation
d. Diffusion and absorption by intestinal cells
e. All of the above

Answer 7

e. All of the above

Question 8

Ethanolamine, serine and choline can be cleaved from glycerophospholipids by treatment with ______.
a. Phospholipase A1
b. Phospholipase A2
c. Phospholipase B
d. Phospholipase C
e. Phospholipase D

Answer 8

e. Phospholipase D

Question 9

Adipocytes contain fat droplets, which serve to provide to an animal ________.
a. Increased cell volume
b. Insulation
c. Chemical energy
d. a and b above
e. b and c above

Answer 9

e. b and c above

Question 10

Triacylglycerols are not found in cell membranes because they are
a. Amphipathic
b. Not amphipathic
c. Not abundant in cells
d. a and c
e. b and c

Answer 10

b. Not amphipathic

Question 11

Polar heads of glycerophospholipids may be _______.
a. + charged
b. - charged
c. Neutral
d. A mixture of + and - charges, but not neutral
e. All of the above

Answer 11

e. All of the above

Question 12

Like plasmologens, sphingolipids are found in relative abundance in ________.
a. Bacteria
b. Plant cells
c. Nerve cells
d. Intestinal cells
e. All of the above

Answer 12

c. Nerve cells

Question 13

An unknown lipid is treated with a mixture of phospholipases A1, A2, C and D. Since no glycerol is formed after this treatment, the lipid is most likely _________.
a. Phosphatidylethanolamine
b. Phosphatidylcholine
c. Plasmologen
d. Ceramide
e. A mixture of a and b

Answer 13

d. Ceramide

Question 14

A deficiency in the synthesis of sphingomyelins or cerebrosides will most likely result in improper formation of ________.
a. Cell surfaces
b. Cell to cell communication
c. Nerve cells
d. Blood groups
e. All of the above

Answer 14

c. Nerve cells

Question 15

What is false - Sterols are steroids, which have _______.
a. A hydroxyl group at position C-17
b. A hydroxyl group at position C-3
c. The ability to accumulate as plaques in blood vessels
d. 5 fused rings instead of 4 fused rings
e. Hydroxyl groups at both position C-3 and C-17

Answer 15

d. 5 fused rings instead of 4 fused rings

Question 16

Cholesterol is converted to cholesteryl esters for ________ in cells and are ________ (more, less) hydrophobic than glycerophospholipids.
a. Transport; more
b. Transport; less
c. Storage; more
d. Storage; less
e. Synthesis; more

Answer 16

c. Storage; more

Question 17

Triacylglycerols cannot form lipid bilayers because they _______.
a. Have hydrophobic tails
b. Do not have polar heads
c. Cannot associate with cholesterol
d. Have polar heads
e. Cannot engage in hydrophobic interactions

Answer 17

b. Do not have polar heads

Question 18

In a typical eukaryotic plasma membrane ________.
a. Oligosaccharides face outward, not toward the cytosol
b. Proteins can move in and out of the bilayer
c. Lipids can move and diffuse through the bilayer
d. Some lipids can rotate within the bilayer
e. All of the above

Answer 18

e. All of the above

Question 19

The arrangement of lipid bilayers and other components is the basis for the currently widely accepted description which is called the
a. Fluid model
b. Lipid bilayer model
c. Mosaic model
d. Diffusion model
e. Fluid mosaic model

Answer 19

e. Fluid mosaic model

Question 20

What is the role of cholesterol in animal cell membranes?
a. Blocks the association of the fatty acyl chains of phospholipids at high temperature.
b. Aids in the transport of small hydrophobic molecules across the membrane.
c. Is a receptor site for hormones on the surface of membranes.
d. Broadens the temperature range of optimum membrane fluidity.

Answer 20

d. Broadens the temperature range of optimum membrane fluidity.

Question 21

Determination of the tertiary structure of a membrane protein finds that the outer surface is composed primarily of hydrophobic residues. Which conclusion is most likely from this observation?
a. It is a lipid-anchored membrane protein.
b. It is an integral protein.
c. The protein must be involved in passive transport.
d. The protein can undergo transverse diffusion.

Answer 21

b. It is an integral protein.

Question 22

Which type of membrane protein might be dissociated from the membrane by changing the pH or the ionic strength?
a. integral membrane protein
b. peripheral membrane protein
c. lipid-anchored membrane protein
d. all of the above

Answer 22

b. peripheral membrane protein

Question 23

You have purified a cell membrane and wish to isolate a transport protein from it. Which treatment might you select?
a. Add a detergent.
b. Change the ionic strength.
c. React with a protease.
d. Add phenylisothiocyanate (PITC).

Answer 23

a. Add a detergent.

Question 24

Which statement is false about lipid-anchored membrane proteins?
a. They are found only on the outer leaflet of the plasma membrane.
b. Like integral membrane proteins, they are permanently associated with the membrane.
c. The covalent link to the membrane involves the phosphate group of the lipid anchor.
d. The protein portion that can be removed by treatment with phospholipase most resembles an integral membrane protein

Answer 24

d. The protein portion that can be removed by treatment with phospholipase most resembles an integral membrane protein

Question 25

Facilitated diffusion (passive transport) through a biological membrane is _____________. a. generally irreversible b. driven by the ATP to ADP conversion c. driven by a concentration gradient d. endergonic

Answer 25

c. driven by a concentration gradient

Question 26

Another name for facilitated diffusion is ___________. a. Active transport b. Transverse diffusion c. Lateral diffusion d. Passive transport

Answer 26

d. Passive transport

Question 27

In the mitochondria phosphate ion (PO43-) and H+ are transported together from the intermembrane space into the matrix. Which statement applies? a. The transport protein is a symport. b. The transport protein must have a relatively large central channel to accommodate both ions. c. The interior of the transport protein must be uncharged. d. All of the above.

Answer 27

a. The transport protein is a symport.

Question 28

If the concentration of a solute is the same both inside and outside the cell, what might you expect with regard to its transport by a membrane protein? a. Since there is no concentration gradient, no transport either in or out of the cell is possible. b. Movement of the solute across the membrane could occur and cause accumulated on one side of the membrane by an active transport protein. c. The transport protein has been saturated. d. The solute must be phosphorylated with a phosphate group from ATP before further transport can occur.

Answer 28

b. Movement of the solute across the membrane could occur and cause accumulated on one side of the membrane by an active transport protein.

Question 29

Which is not a similarity between active transport proteins and enzymes? a. Both undergo conformational changes upon binding a substrate. b. Both are susceptible to inhibition. c. Both cause chemical modification to the substrate. d. Both can reach a saturation limit.

Answer 29

c. Both cause chemical modification to the substrate.

Question 30

The membrane transport protein Na+-K+ ATPase carries both Na+ and K+ ions across the plasma membrane. Typically the concentration of K+ inside cells is about 30 times higher inside the cell than outside. The concentration of Na+ is about 20 times less inside the cell than outside. Based on this information, which statement below is false? a. The proper functioning of Na+-K+ ATPase could serve as an energy source for secondary active transport proteins. b. It is a symport. c. Transport of Na+ and K+ must be coupled to an exergonic reaction. d. Na+-K+ ATPase likely undergoes conformational changes during transport.

Answer 30

b. It is a symport.

Question 31

Very large molecules (macromolecules) can be transported across membranes by _________. a. pores or channels with very large openings through the center b. active transport proteins c. diffusion down a concentration gradient d. endocytosis or exocytosis

Answer 31

d. endocytosis or exocytosis

Question 32

Fatty acids such as linolenate can assume a variety of steric configurations. a. True b. False

Answer 32

a. True

Question 33

Lipids derived from cholesterol aid digestion and absorption of other lipids such as triacylglycerols. a. True b. False

Answer 33

a. True

Question 34

All sphingolipids are made from ceramides. a. True b. False

Answer 34

a. True

Question 35

Steroids are isoprenoids because they are composed of repeated subunits of isoprene. a. True b. False

Answer 35

a. True

Question 36

Aspirin can alleviates clinical symptoms of pain and fever because it inhibits the synthesis of certain eicosanoids. a. True b. False

Answer 36

a. True

Question 37

According to the current model of cell membrane structure, the two layers of lipids in the bilayer are nearly identical chemically. a. True b. False

Answer 37

b. False

Question 38

The membrane-spanning portion of a transmembrane protein is almost always a ·-strand. a. True b. False

Answer 38

b. False

Question 39

Cholesterol accounts for 20 - 25% of the mass of lipids in a typical mammalian plasma membrane. a. True b. False

Answer 39

a. True

Question 40

The distribution of peripheral membrane proteins is generally identical on both sides of a given membrane. a. True b. False

Answer 40

b. False

Question 41

Transport of ions and small molecules through a bacterial membrane pore requires energy from an ATP hydrolysis. a. True b. False

Answer 41

b. False

Question 42

The formation of a specialized lipid vesicle for the transport of a toxic protein out of a cell is called endocytosis. a. True b. False

Answer 42

b. False

Question 43

Symport and antiport proteins must be active transport proteins. a. True b. False

Answer 43

a. True