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Biochemistry > Lipids > Flashcards

Lipids Flashcards

1
Q

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

A

d. Amphipathic

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2
Q

_____ 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

A

d. Fatty acids

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3
Q

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

A

d. a and c

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4
Q

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

A

c. Saturated; unsaturated

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5
Q

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

A

c. unsaturated fatty acids

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6
Q

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

A

d. Essential lipids

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7
Q

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

A

e. All of the above

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8
Q

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

A

e. Phospholipase D

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9
Q

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

A

e. b and c above

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10
Q

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

A

b. Not amphipathic

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11
Q

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

A

e. All of the above

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12
Q

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

A

c. Nerve cells

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13
Q

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

A

d. Ceramide

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14
Q

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

A

c. Nerve cells

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15
Q

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

A

d. 5 fused rings instead of 4 fused rings

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16
Q

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

A

c. Storage; more

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17
Q

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

A

b. Do not have polar heads

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18
Q

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

A

e. All of the above

19
Q

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

A

e. Fluid mosaic model

20
Q

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.

A

d. Broadens the temperature range of optimum membrane fluidity.

21
Q

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.

A

b. It is an integral protein.

22
Q

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

A

b. peripheral membrane protein

23
Q

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).

A

a. Add a detergent.

24
Q

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

A

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

25
Q

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

A

c. driven by a concentration gradient

26
Q

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

A

d. Passive transport

27
Q

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.

A

a. The transport protein is a symport.

28
Q

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.

A

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

29
Q

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.

A

c. Both cause chemical modification to the substrate.

30
Q

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.

A

b. It is a symport.

31
Q

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

A

d. endocytosis or exocytosis

32
Q

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

A

a. True

33
Q

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

A

a. True

34
Q

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

A

a. True

35
Q

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

A

a. True

36
Q

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

A

a. True

37
Q

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

A

b. False

38
Q

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

A

b. False

39
Q

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

A

a. True

40
Q

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

A

b. False

41
Q

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

A

b. False

42
Q

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

A

b. False

43
Q

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

A

a. True

Biochemistry (10 decks)

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