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Biomolecules > Lipids: Structure and Function > Flashcards

Lipids: Structure and Function Flashcards

1
Q

What is the basis of classifying lipids together?

A

Their insolubility in water

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2
Q

Fatty acids are carbonyl acids with hydrocarbon chains ranging from 4 to 24 carbons long. T/F

A

F

They are carboxyl acids with hydrocarbon chains ranging from 4 to 36 carbons long

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3
Q

In the notation 18: 1 (Δ^9) cis-9 Octadecenoic acid,

how many carbons are in the hydrocarbon chain? How many double bonds, and where are they located?

A

18 carbons

One double bond at the 9th carbon

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4
Q

The most commonly occurring fatty acid in an unbranched chain has how many carbons?

A

12 to 24

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5
Q

Most monounsaturated fatty acids have their double bonds on which carbon?

A

Between C-9 and C-10

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6
Q

The double bonds on polyunsaturated fatty acids are generally on which carbons?

A

C-12 and C-15

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7
Q

Which polyunsaturated fatty acid does not have its double bonds on C-12 or C-15?

A

Arachidonic acid

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8
Q

The double bonds of polyunsaturated fatty acids are separated by which functional group?

A

Methylene group

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9
Q

The double bonds of all natural occurring unsaturated fatty acids are in the trans configuration. T/F

A

F

They are in cis.

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10
Q

Which carbon is called omega carbon?

A

The carbon of the methyl group, that is, the carbon most distant from the carboxyl group

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11
Q

Which polyunsaturated fatty acids (PUFAs) are called omega-3 fatty acids?

A

PUFAs with double bonds between C-3 and C-4

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12
Q

Which PUFAs are called omega-6 fatty acids?

A

PUFAs with double bonds between C-6 and C-7

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13
Q

The shorter the fatty acyl chain, and the fewer the double bonds, the lower is the solubility in water of lipids. T/F

A

F

The longer the fatty acyl chain, and the fewer the double bonds, the lower is the solubility in water.

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14
Q

At 25 degrees Celsiud, the saturated fats from 12:0 to 24:0 have a waxy consistency whereas unsaturated fatty acids of these lengths are in what phase?

A

Liquid

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15
Q

What structural configuration causes the kink in the hydrocarbon chains of unsaturated fatty acids?

A

Cis double bonds

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16
Q

Why do unsaturated fatty acids have low melting points?

A

They have cis double bonds that causes kinks in their hydrocarbon chain. These kinks weaken the interaction of the molecules to each other, preventing the tightly packing of the fatty acids. Weak interaction between molecules require less thermal energy to break them apart, causing the low melting point of unsaturated fatty acids.

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17
Q

The simplest lipids constructed from fatty acids

A

Triacylglycerols or triglycerides (or fats or neutral fats)

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18
Q

Components of the triglyceride molecule

A

Three fatty acids linked to glycerol molecule by ester linkage

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19
Q

Sphingolipids have glycerol. T/F

A

F

Sphingolipids are composed of sphingosine and a polar head group.

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20
Q

Which compound is ths structural parent of all sphingolipids?

A

Ceramide

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21
Q

Which of the following statements about trans fatty acid is false?

a. Cis-Oleic acid has a higher melting point than Trans-Elaidic Acid
b. Trans fatty acid can be synthesized through the process of hydrogenation
c. May lead to cardiovascular disease
d. Ruminant animals as good source

A

A

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22
Q

Which of the following molecules would be the MOST hydrophobic?

A. Triacylglycerol
B. Cysteine
C. Glucose
D. Aspartic acid

A

A

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23
Q

Which is TRUE regarding fatty acids?

A. Double bonds confer a higher melting point.
B. Naturally occurring unsaturated fatty acids have cis double bonds.
C. Saturated fatty acids are responsible for membrane fluidity.
D. Monounsaturated fatty acids have an extended all trans conformation.

A

B

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24
Q

Coconut oil is liquid at room temperature yet it contains very small amount of unsaturated fatty acids. Which statement BEST explains this physical state of coconut oil?

A. It contains a lot of long-chain saturated fatty acids.
B. It contains mostly cholesterol esters.
C. It contains mostly short and medium chain fatty acids.
D. It contains trans fatty acids.

A

C

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25
Q

Which of the following statements is NOT TRUE about trans fatty acids?

A. Some trans fatty acids are found in foods derived from ruminant animals.
B. Elaidic acid , an 18:1∆^9 trans fatty acid exhibit higher melting point than oleic acid, another 18:1∆^9 fatty acid
C. Trans fatty acid are produced by hydrogenation of saturated fatty acids.
D. Trans fatty acids increase the risk for cardiovascular disease.

A

A

26
Q

Which of the following molecules is most hydrophobic?

A. Triacylglycerol
B. Methionine
C. D-glucose
D. Glutamic acid

A

A

27
Q

Which of the following molecules would most likely participate in the formation of a lipid bilayer?

A. Triacylglycerol
B. Phospholipid
C. Palmitic acid
D. All of them are equally likely to form lipid bilayers

A

B

28
Q

Hormones like insulin are commonly secreted from cells by means of vacuolar transport. Of the following conditions of phospholipids, which is most relevant in this form of transport?

A. Micelles
B. Monolayers
C. Bilayers
D. A & C

A

C

29
Q

Which of the following biomolecules DOES NOT have a sugar moiety?

a. ATP
b. NADH
c. Sphingosine
d. Mucin

A

C

30
Q

Which is TRUE of fatty acids?

A. Double bonds confer higher melting points
B. Unsaturated fatty acids have cis double bonds
C. Saturated fatty acids provide membrane fluidity
D. Transport in blood occurs in free fatty acid form only

A

B

31
Q

Which of the following statements best describes the essential fatty acids

A. Important sources of essential fatty acids are animal fats
B. Linolenic acid and oleic acids are examples of essential fatty acids
C. Essential fatty acids are precursors of LCPUFA (Long
chain polyunsaturated fatty acids)
D. All essential fatty acids are omega-3 fatty acids

A

C

32
Q

Rank the following lipids in the order of increasing solubility in water:

  1. Monoacylglycerol
  2. Glycerol
  3. Diacylglycerol
  4. Triacylglycerol

A. 1, 2, 3, 4
B. 4, 3, 2, 1
C. 4, 3, 1, 2
D. 2, 1, 4, 3

A

C

33
Q

Which of the following lipids does not have a fatty acid component?

A. Ganglioside GM2
B. Waxes
C. Lecithin
D. Vitamin K

A

D

34
Q

Which of the following statements best describes phospholipids?

A. The alcohol backbone of all phospholipids is glycerol
B. The carbohydrates heads are oriented extracellulary and the nonpolar tails are projected into the cytoplasm
C. Its phosphoryl-base components make up its polar head group
D. Together with triglycerides they are the major lipid components of membranes

A

C

35
Q

Which properties of phospholipids govern lipid aggregation into higher ordered structures?

A. Amphipathic property
B. Spontaneous self-sealing and self-assembly
C. Hydrophobicity
D. All of the above
E. A & B only
A

E

36
Q

Which is not a function of omega-6?

A. Membrane
B. Growth
C. Brain Development
D. Prevents dermatitis

A

C

37
Q

Eating food rich in fats may have several effects in our body. Which of the following dietary fatty acids is known for its health benefits in lowering serum triglycerides?

A. Palmitic acid
B. Dieic acid
C. Linoleic acid
D. Eicosapentanoic acid

A

D

38
Q
  1. Which statement is true about the role of DHA in infant development and nutrition?

A. It accumulates during the second trimester.
B. It is associated with brain development and visual acuity.
C. It is recommended in formula milk for preterm babies.
D. All of the above.
E. B and C only.

A

E

39
Q

Hormone-like fatty acid derivatives that act on nearby tissue are locally acting messenger molecules which target cells in immediate vicinity.

A. Gangliosides
B. Vitamins K and E
C. DAG and inositol 1,4,5-trisphosphate
D. Eicosanoids

A

D

40
Q

Contains N-acetylneuraminic acid moiety

A. Gangliosides
B. Vitamins K and E
C. DAG and inositol 1,4,5-trisphosphate
D. Eicosanoids

A

A

41
Q

Isoprenoids obtained from diet

A. Gangliosides
B. Vitamins K and E
C. DAG and inositol 1,4,5-trisphosphate
D. Eicosanoids

A

B

42
Q

2nd messenger produced by bioeffector lipids

A. Gangliosides
B. Vitamins K and E
C. DAG and inositol 1,4,5-trisphosphate
D. Eicosanoids

A

C

43
Q

Omega 3 Long chain PUFAs have become a fad for good health. Several commercial products claim to contain these so-called beneficial fats. Which of the ff is true regarding these fatty acids?

A. It can be synthesized in humans de novo
B. It can be found in deep sea fishes but not in plants
C. They can be synthesized in the human body only
when the initial precursors are acquired from the diet
D. The initial precursors are oleic acid and cholesterol free diet

A

C

44
Q

Respiratory distress syndrome occurs in premature infants who lack surfactant. Which of the lipids given below is associated with its lung surfactant function?

A. Cholesterol esters
B. Dipalmitoyllecithin (a phospholipid)
C. Phosphatidyl Inositol
D. Ganglioside GM2

A

B

45
Q

Which of the following statement/s BEST describe/s the role of cholesterol in modifying membrane fluidity by varying phase transition temperature (Tm)?

A. Below the Tm, cholesterol increases membrane fluidity by interfering with the rigid hydrocarbon tails of the phospholipids.
B. Above the Tm, cholesterol decreases the membrane fluidity by limiting the motion or disorder of the hydrocarbon tails .
C. At the Tm, cholesterol cannot insert itself in the membrane.
D. All of the above
E. A and B only

A

E

46
Q

Isoprenoids that must be obtained in the diet

A. Testosterone and cortisol
B. Phosphatidyl inositol and derivatives
C. Vitamin K and Vitamin E
D. Eicosanoids

A

C

47
Q

Bioeffector lipid precursors that produce second messengers

A. Testosterone and cortisol
B. Phosphatidyl inositol and derivatives
C. Vitamin K and Vitamin E
D. Eicosanoids

A

B

48
Q

Steroid hormones

A. Testosterone and cortisol
B. Phosphatidyl inositol and derivatives
C. Vitamin K and Vitamin E
D. Eicosanoids

A

A

49
Q

Stearic acid can be converted to oleic acid. T/F

A

T

50
Q

Olive oil is a primary source of which fatty acid?

A

Oleic

51
Q

Walnuts is a source of which fa?

A

alpha-linolenic acid

52
Q

The more unsaturated the fa, the harder it is to oxidize. T/F

A

F

The more unsaturated the fa, the easier to oxidize.

53
Q

Which of the following fatty acids has the lowest melting point?

A. C20:4; Δ5, 8, 11, 14
B. C18:2; Δ9, 14
C. C18:1; Δ9
D. C16:0

A

A

54
Q

Palmitic Acid: A

A. 16:0
B. 18:2
C. 20:4
D. 18:1

A

A

55
Q

Linoleic Acid:

A. 16:0
B. 18:2
C. 20:4
D. 18:1

A

B

56
Q

Arachidonic Acid:

A. 16:0
B. 18:2
C. 20:4
D. 18:1

A

C

57
Q

Oleic Acid:

A. 16:0
B. 18:2
C. 20:4
D. 18:1

A

D

58
Q

Which of the following is a secosteroid?

A. Cortisol
B. Progesterone
C. Testosterone
D. Calcitriol

A

D

Secosteroids are steroid compounds that have an open ring. Only calcitriol has an open ring.

59
Q

What hormone forms a hormone-receptor complex that acts directly on a DNA segment?

A. T3
B. Calcitrol
C. Estradiol

A

C

60
Q

Which of the following is an essential fatty acid?

A. Erucic Acid
B. Linoleic Acid
C. Oleic Acid
D. Palmitic Acid

A

B

Biomolecules (4 decks)

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