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Biochemistry > Lipids (1) > Flashcards

Lipids (1) Flashcards

1
Q

A lipid is any substance of biochemical origin that is ___

  • insoluble in nonpolar solvents but soluble in water
  • insoluble in both water and polar solvents
  • insoluble in water but soluble in nonpolar solvents
  • soluble in both water and nonpolar solvents
A

insoluble in water but soluble in nonpolar solvents

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2
Q

Which of the following fatty acids is both monosaturated and an omega-6fatty acid?

  • CH3-(CH2)18-COOH
  • CH3-(CH2)7-CH=CH-(CH2)6-COOH
  • CH3-(CH2)4-CH=CH-(CH2)6-COOH
  • CH3-CH2-(CH=CH-CH2)4-(CH2)2-COOH
A

CH3-(CH2)4-CH=CH-(CH2)6-COOH

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3
Q

Which of the following is true of most fatty acids found in triglycerides?

  • they are unbranched
  • they contain more than 20 carbon atoms
  • they contain an odd number of carbon atom
  • none of the above
A

they are unbranched

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4
Q

How do simple triacylglycerols (STAG) differ from mixed triacylglycerols (MTAGs)?

  • STAGS contain short-then fatty acids and MTAGS contain long-chain fatty acids
  • STAG contains unbranched fatty acids and MTAGS contains branched fatty acids.
  • STADS contain saturated fatty acids and MTAGS contain saturated fatty acids
  • STAGS contain only one kind of fatty acid and MTAGS contain more than one kind of fatty acid
A

STAGS contain only one kind of fatty acid and MTAGS contain more than one kind of fatty acid

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5
Q

which of the following is true of the unsaturated fatty acids in triglycerides?

  • the double bond generally has the cis-configuration
  • the double bond generally has the trans-configuration
  • there approximately equal number of cis and trans arrangement
  • they always contain more than one double bond
A

the double bond generally has the cis-configuration

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6
Q

What process may be used to convert ean unsaturated fatty acid into a saturated fatty acid?

  • combustion
  • esterification
  • hydrolysis
  • hydrogenation
A
  • hydrogenation
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7
Q

The products of the hydrolysis of oil are three fatty acids and ___

  • long chain alcohol
  • glycerol
  • phosphoric acid
  • amino alcohol
A
  • glycerol
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8
Q

Which of the following types of compounds are expected products from the saponification of an oil?

  • glycerol and fatty acids
  • glycerol and fatty acid salts
  • fatty acid salts and fatty ac
  • fatty acids and glycine
A
  • glycerol and fatty acid salts
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9
Q

partial hydrogenation of a fat or oil

  • A produces fatty acid salts
  • increases the degree of fatty acid unsaturation
  • increases the melting point
  • more than one correct response
A

increases the melting point

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10
Q

Which of the following statements concerning fatty acids is incorrect?

  • Some fatty acids needed in the human body must be obtained from food because they cannot be synthesized with the body
  • Fatty acids are rarely found in the free state in nature
  • At least 16 carbon atoms must be present in the carbon chain of a fatty acid
  • Double bonds present in fatty acids are almost always in a cis-configuration
A
  • At least 16 carbon atoms must be present in the carbon chain of a fatty acid
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11
Q

In a glycerophospholipid, glycerin’s three -OH groups are esterified, respectively, with

  • one fatty acid and two phosphoric acid molecules
  • two fatty acids and one phosphoric acid molecule
  • three phosphoric acid molecules
  • one fatty acid, one phosphoric acid, and one amino alcohol molecules
A
  • two fatty acids and one phosphoric acid molecule
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12
Q

Which of the following best describes the components of phospholipids?

  • glycerol, one fatty acid, two phosphate groups, and an alcohol
  • glycerol, two fatty acids, a phosphate group, and an alcohol
  • either of these, depending on the identity of the phospholipid
  • none of the above
A
  • glycerol, two fatty acids, a phosphate group, and an alcohol
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13
Q

Which of the following statements concerning eicosanoids is correct?

  • The precursor of most eicosanoids is cholesterol.
  • Eicosanoids are hormones transported in the blood to their site of action.
  • Both thromboxanes and leukotrienes are types of eicosanoids.
  • None of the above
A
  • Both thromboxanes and leukotrienes are types of eicosanoids.
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14
Q

Which kind of eicosanoids is thought to promote certain aspects of the inflammatory response?

  • leukotrienes
  • thromoboxanes
  • steroids
  • prostaglandins
A
  • prostaglandins
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15
Q

Which lipid hormones allow tissues of the body to communicate with one another?
- lipoproteins
- prostaglandins
- steroids
- arachidonates

A
  • steroids
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16
Q

In which of the following types of lipids are two ester linkages and one amide linkage present? - - Glycerophospholipids
- sphingophospholipids
- sphingoglycolipids
- triacylglycerols

A
  • sphingophospholipids
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17
Q

Which of the following provides a mechanism for the transport of nonpolar molecules through a membrane?
- active transport
- diffusion
- specific channels
- all of this

A
  • diffusion
18
Q

Which of the following is choline?
- HOCH2CH2NH2
- HOCH2CHCOO
NH
- [HOCH2CH2N(CH3)3] ^+
- none of these

A

[HOCH2CH2N(CH3)3] *

19
Q

Myelin, the coating of nerve axons, is which type of lipid?
- Cephalin
- lecithin
- simple lipid
- sphingolipid

A
  • sphingolipid
20
Q

Which of the following is not found in cerebrosides?
- an amide linkage
- a carbohydrate
- a hydroxyl group
- a phosphate group

A
  • a phosphate group
21
Q

Which of the following is found in glycolipids but not in other complex lipids?
- a carbohydrate
- a fatty acid
- sphingosine
- none

A
  • a carbohydrate
22
Q

Eicosanoids are oxygenated derivatives of
- cholesterol
- glycerophospholipids
- polyunsaturated 20-carbon fatty acids
- saturated fatty acids with less than 18 carbon atoms

A
  • polyunsaturated 20-carbon fatty acids
23
Q

Which of the following describes the distribution of the polar and nonpolar portions of lipids in the lipid bilayer?
- both polar heads are on the inside of the bilayer and both hydrophobic tails are on the outside of the bilayer
- both polar heads are on the outside of the bilayer and both hydrophobic tails are on the inside of the bilayer
- both the inside and outside of the bilayer consist of alternating polar heads and nonpolar tails
- some polar heads are on the inside of the bilayer and some are on the outside; the hydrophobic tails are similarly distributed

A
  • both polar heads are on the outside of the bilayer and both hydrophobic tails are on the inside of the bilayer
24
Q

Which of the following is a function of unsaturated fatty acids in membranes?
- they give the interior of the membrane a liquid-like structure
- they provide a site for chemical reactions to occur
- both (a) and (b)
- neither (a) nor (b)

A
  • they give the interior of the membrane a liquid-like structure
25
Q

Which of the following provides a mechanism for the transport of ions and polar molecules through a membrane?
- active transport
- specific channels
- both (a) and (b)
- neither (a) nor (b)

A
  • both (a) and (b)
26
Q

Cholesterol is used as which of the following?
- a component of plasma membranes
- a starting material for the synthesis of other steroids
- a starting material for the synthesis of bile salts
- all of these

A
  • all of these
27
Q

Which of the following carries cholesterol to the cells?
- chylomicrons
- HDL
- LDL
- VLDL

A
  • LDL
28
Q

Which of the following transports cholesterol to the liver?
- chylomicrons
- HDL
- LDL
- VLDL

A
  • HDL
29
Q

Which of the following is the result of high cholesterol levels inside cells?
- cholesterol synthesis in the liver ceases completely
- cholesterol synthesis in the liver increases
- less LDL is taken into the cells from the plasma
- more LDL is taken into the cells from the plasma

A
  • less LDL is taken into the cells from the plasma
30
Q

Which of the following substances do not contribute to the structure of biological membranes?
- phospholipids
- glycolipids
- cholesterol
- cellulose

A
  • cellulose
31
Q

Which of the following will most directly result in an increase in the amount of cholesterol synthesized in the liver?
- the cholesterol level inside cells
- the cholesterol level in blood serum
- the ratio of HDL to LDL
- all of these are equally important

A
  • the cholesterol level in blood serum
32
Q

In which of the following ways do bile salts remove excess cholesterol?
- cholesterol is converted to bile salts which are then eliminated in the feces
- bile salts convert LDL to HDL
- both (a) and (b)
- neither (a) nor (b)

A
  • cholesterol is converted to bile salts which are then eliminated in the feces
33
Q

Which of the following is found in thromboxanes?
- B-lactam
- a cyclic acetal
- a cyclic ether
- none of these

A
  • a cyclic acetal
34
Q

Which of the following is(are) associated with a build-up of leukotrienes?
- asthma-like attacks
- fever
- inflammation
- all of these

A
  • all of these
35
Q

Statements:
X (1) Fats and oils have the same general chemical structure.
(2) Biological waxes have a three-component “block diagram.”
(3) In facilitated transport, a substance crosses a cell membrane with the help of a protein “pump.”

  • All three statements are true.
  • Two of the three statements are true.
  • Only one of the statements is true.
  • None of the statements are true.
A
  • Only one of the statements is true.
36
Q

Statements:
(1) Steroids have structures based on a fused-three-ring system.
(2) Glycerophospholipids and sphingophospholipids both have “head-and-two-tails” structures.
(3) Both fats and oils are TAG mixtures.

  • All three statements are true.
  • Two of the three statements are true.
  • Only one of the statements is true.
  • None of the statements are true.
A
  • Two of the three statements are true.
37
Q

(1) Triacylglycerols can be hydrolyzed under acidic conditions to produce salts of fatty acids.
(2) Hydrogenation of a fat or oil increases its degree of unsaturation.
(3) Eicosanoids are oxygenated derivatives of polyunsaturated 18-carbon fatty acids.

  • All three statements are true.
  • Two of the three statements are true.
  • Only one of the statements is true.
  • None of the statements are true.
A
  • None of the statements are true.
38
Q

1) Cholesterol is both a steroid and a membrane lipid.
(2) Sphingoglycolipids are components of cell membranes.
(3) Sphingosine, the “platform” for sphingolipids, is an amino dialcohol.

  • All three statements are true.
  • Two of the three statements are true.
  • Only one of the statements is true.
  • None of the statements are true.
A
  • All three statements are true.
39
Q

(1) Omega-3 fatty acids are unsaturated fatty acids containing three double bonds.
(2) Prostaglandins and thromboxanes are classes of eicosanoids.
(3) In general, lipids are substances that are only sparingly soluble in water

  • All three statements are true.
  • Two of the three statements are true.
  • Only one of the statements is true.
  • None of the statements are true.
A
  • Two of the three statements are true.
40
Q

(1) In active transport, a substance crosses a cell membrane against a concentration gradient.
(2) Fatty acid melting point decreases with increasing degree of unsaturation.
(3) Complete hydrolysis of a TAG produces four product molecules, all of which must be different from each other.

  • All three statements are true.
  • Two of the three statements are true.
  • Only one of the statements is true.
  • None of the statements are true.
A
  • Two of the three statements are true.
41
Q

(1) Structurally, fats contain three ester linkages and oils contain only two ester linkages.
(2) Hormones, many of which are steroids, are chemical messengers produced by ductless glands.
(3) The configuration of double bonds in naturally occurring unsaturated fatty acids is almost always trans.

  • All three statements are true.
  • Two of the three statements are true.
  • Only one of the statements is true.
  • None of the statements are true.
A
  • Only one of the statements is true.
42
Q

(1) The “head group” in sphingolipids can be a small carbohydrate molecule.
(2) Biological waxes have structures in which an amide linkage is present.
(3) An 18:3 fatty acid contains more unsaturation than a 20:2 fatty acid.

  • All three statements are true.
  • Two of the three statements are true.
  • Only one of the statements is true.
  • None of the statements are true.
A
  • Two of the three statements are true.

Biochemistry (10 decks)

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