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Biochem 2 (CHEM 441B) > Ch. 15 > Flashcards

Ch. 15 Flashcards

1
Q

What are the types of fatty acids?

A
  • Saturated fatty acids
  • Unsaturated fatty acids (monounsaturated and polyunsaturated)
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2
Q
A

Myristate; 14:0

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3
Q
A

Palmitate; 16:0

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4
Q
A

Stearate; 18:0

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5
Q
A

Oleate

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6
Q
A

Arachidonate

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7
Q

What are saturated fatty acids?

A

Hydrocarbon chain contains only fully reduced methylene groups (no double bonds)

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8
Q

What are unsaturated fatty acids?

A

1 or more C=C double bonds in hydrocarbon chain

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9
Q

What are monounsaturated fatty acids?

A

Contain 1 C=C double bonds in hydrocarbon chain

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10
Q

What are polyunsaturated fatty acids?

A

Contain multiple C=C double bonds in hydrocarbon chain

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11
Q

What are essential fatty acids?

A

Humans must obtain them in diet because we don’t have the enzymes to synthesize them

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12
Q

List some essential fatty acids.

A
  • Linoleate
  • α-linolenate
  • Arachidonate
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13
Q

What does a cis isomer look like?

A
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14
Q

What does a trans isomer look like?

A
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15
Q

Are most fatty acids cis or trans?

A

Cis

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16
Q

Do long-chain saturated fatty acids have a higher or lower melting point than long-chain unsaturated fatty acids? Why?

A

Higher MP because of differences in intermolecular interactions

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17
Q

TAGs containing mostly saturated fatty acids have a _____ MP.

A

Higher

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18
Q

TAGs containing mostly unsaturated fatty acids have a _____ MP.

A

Lower

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19
Q

What is hydrogenation?

A

Process of heating unsaturated fatty acids in presence of hydrogen to reduce C=C double bonds (increase degree of saturation)

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20
Q

What is a trans fat?

A

Unsaturated fatty acid where C=C double bond is in the trans configuration instead of cis

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21
Q

Do plant vs. animal trans fats pose the same risks?

A

Yes

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22
Q

How are carbons in fatty acids usually numbered?

A

From carboxylic acid end (carboxyl carbon is C-1)

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23
Q

How are positions of C=C bonds in polyunsaturated fatty acids often identified?

A

Identified using methyl carbon (omega-carbon)

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24
Q

What is an omega-6 fatty acid?

A

Unsaturated fatty acid where the double bond is 6 carbons away from the terminal methyl carbon

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25
Q

What is an example of an omega-6 fatty acid?

A

Linoleic acid

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26
Q

What is an omega-3 fatty acid?

A

Unsaturated fatty acid where the double bond is 3 carbons away from the terminal methyl carbon

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27
Q

What is an example of an omega-3 fatty acid?

A

α-linoleic acid

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28
Q

What is α-linoleic acid converted to?

A

Eicosapentaenoic acid (EPA) and docosahexanoic acid (DHA)

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29
Q

Why are omega-3 fatty acids good?

A

They’re associated with a decreased risk of cardiovascular disease

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30
Q

What is lipidomics?

A

Large-scale investigation of structures and functions of the complete set of lipids in a biological system

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31
Q

What are waxes?

A

Lipid composed of long-chain fatty alcohols esterified to long-chain fatty acids

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32
Q

Why are waxes solids in biological contexts?

A

The MP of long-chain saturated wax esters is usually higher than ambient temperature

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33
Q

What are adipocytes?

A

Fat cell; site of TAG storage

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34
Q

Why are TAGs a major form of stored energy?

A
  • Fatty acids are at a higher reduction state than glucose, so they yield more energy per number of carbons upon oxidation in mitochondrial matrix
  • Hydrophobic nature means they are not solvated by water so they have less mass for the same amount of stored energy as glycogen
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35
Q

Where do we obtain TAGs from?

A

Diet or synthesized in liver

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36
Q

What is a lipoprotein?

A

Molecular complex made of hydrophobic lipid core surrounded by shell of polar lipids and apolipoproteins

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37
Q

What transports dietary TAGs?

A

Chylomicrons

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38
Q

What are lipases?

A

Water-soluble enzyme that hydrolyzes TAGs into free fatty acids and glycerol

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39
Q

What is colipase?

A

Regulatory protein associated with pancreatic lipase
- Enhances lipase function by binding bile acids, which inhibit lipase function

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40
Q

What are chylomicrons?

A

Large lipoprotein particles that transport TAGs from intestines to tissues throughout body

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41
Q

What do apolipoproteins do?

A

Promote lipoprotein particle formation in endomembrane system

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42
Q

Biosynthesis of TAGs in animals uses __1__ produced by degradation of __2__ and __3__ to generate __4__ in cytosol.

A
  1. Acetyl-CoA
  2. Carbs
  3. Proteins
  4. Palmitate
43
Q

What are lipid droplets?

A

Aggregate of TAG molecules surrounded by phospholipid monolayer in adipocyte cytoplasm
- Where TAGs are stored

44
Q

What is perilipin?

A

Monolayer-embedded protein forming shell of adipocyte lipid droplets
- Prevents TAG degradation by endogenous adipocyte lipases

45
Q

What are the 3 major lipases in human adipocytes?

A
  1. Adipose triglyceride lipase
  2. Hormone-sensitive lipase
  3. Monoacylglycerol lipase
46
Q

How does glucagon signaling lead to fatty acid release into the bloodstream?

A
  1. Activation of the glucagon receptor leads to GDP–GTP exchange in the Gsα protein, which stimulates cyclic AMP production by the enzyme adenylate cyclase
  2. Glucagon downstream signal is transmitted by cyclic AMP activation of PKA, which phosphorylates perilipin on the surface of lipid droplets and hormone-sensitive lipase
  3. Conformational change that promotes binding of regulatory protein G58 to adipose triglyceride lipase
  4. Hydrolysis reaction that cleaves a fatty acid from the stored triacylglycerols to generate diacylglycerol and a free fatty acids
  5. Phosphorylated hormone-sensitive lipase also associates with perilipin on the lipid droplet surface, where it produces a free fatty acid from diacylglycerol to produce monoacylglycerol
  6. Monoacylglycerol lipase then generates a free fatty acid and glycerol from monoacylglycerol
  7. Albumin transports the free fatty acids through the circulatory system to tissue
47
Q
48
Q
A

Triacylglycerol

49
Q

What are the 3 major types of membrane lipids?

A
  1. Glycerophospholipids
  2. Sphingolipids
  3. Cholesterol
50
Q

What are glycerophospholipids?

A

Membrane lipid composed of glycerol linked to 2 fatty acid chains and a phosphate group, which is bound to a polar head moiety

51
Q

What are the 4 types of glycerophospholipids?

A
  1. Phosphatidylcholine
  2. Phosphatidylserine
  3. Phosphatidylethanolamine
  4. Phosphatidylinositol
52
Q

What are sphingolipids?

A

Molecules containing sphingosine bound to a single fatty acid chain

53
Q

What are sphingophospholipids?

A

Sphingolipids linked to a phosphate group that’s connected to a polar head group
- Sphingomyelin

54
Q

What are the 2 types of sphingolipids?

A
  1. Sphingophospholipids
  2. Sphingoglycolipids
55
Q

What are the 2 types of sphingoglycolipids?

A
  1. Cerebrosides
  2. Gangliosides
56
Q

What kind of lipid are cerebrosides? What is the general structure of cerebrosides?

A
  • Type of sphingolipid
  • Contain glucose or galactose bound to the terminal hydroxyl group
57
Q

What are gangliosides?

A

Cerebrosides with an oligosaccharide bound to the terminal glucose or galactose

58
Q

What is the fluid mosaic model?

A

Membrane is a 2D solution in which many membrane proteins are both oriented across the membrane and free to move laterally through the membrane

59
Q

What are lipids rafts?

A

Aggregation of membrane proteins that form densely packed complexes

60
Q

What is the function of lipid rafts?

A

Thought to serve as sites for cell signaling, membrane trafficking, and neurotransmission

61
Q

What is the most abundant membrane lipid?

A

Glycerophospholipids

62
Q

What is phosphotidate a precursor for?

A

Precursor for many common glycerophospholipids

63
Q

What is this?

A

Phosphotidate

64
Q

What is 1?

A

Phosphatidylserine

65
Q

What is 2?

A

Phosphatidylethanolamine

66
Q

What is 3?

A

Phosphatidylcholine

67
Q

What is 4?

A

Phosphatidylinositol

68
Q

Identify the sites of phospholipase action.

69
Q

What is sphingosine?

A

Long-chain amino alcohol derived from palmitate

70
Q

What is ceramide a precursor for? What is its structure?

A
  • Precursor of cerebrosides, gangliosides, and sphingolipids
  • Sphingosine covalently linked to a fatty acid
71
Q
72
Q
A

Sphingomyelin

73
Q

What do gangliosides have a role in?

A

Cell recognition and membrane function

74
Q

What is Tay-Sachs disease?

A

Genetic disease of sphingolipid metabolism due to defective hexosaminidase A, which causes GM2 gangliosides to accumulate

75
Q

What is Fabry disease?

A

Genetic disease of sphingolipid metabolism due to a defect in α-galactosidase A, which causes ceramide trihexoside to accumulate

76
Q

What is Niemann-Pick disease?

A

Genetic disease of sphingolipid metabolism due to a mutation in the gene for sphingomyelinase, which blocks the conversion of sphingomyelin to ceramide

77
Q

What causes the symptoms of Tay Sachs disease vs. Fabry disease and Niemann-Pick disease?

A
  • Tay-Sachs sympotoms are due to excess levels of the GM2 substrate
  • Fabry and Niemann-Pick symptoms are due to the accumulation of metabolic precursors
78
Q
A

Cholesterol

79
Q

What are eicosanoids?

A

Group of immune system signaling molecules derived from long-chain polyunsaturated fatty acids

80
Q

What do cholesterol derivatives regulate?

A

Activity of nuclear receptor proteins

81
Q

What are bile acids?

A

Polar molecules derived from cholesterol that are secreted into intestines where they emulsify dietary lipids (aids in lipid absorption)

82
Q

What is the major bile acid in humans?

A

Glycocholate

83
Q

What are steroid hormones?

A

Ligands for nuclear receptor proteins, which mediate hormone signals by altering the expression of specific genes

84
Q

What is rickets?

A

Disease caused by vitamin D deficiency
- Results in inadequate calcium deposition in cartilage and bone

85
Q

Where does over 90% of vitamin D in the human body come from?

A

Sunlight conversion of 7-dehydrocholesterol

86
Q
A

7-Dehydrocholesterol

87
Q
A

Vitamin D3

88
Q
A

25-Hydroxyvitamin D3

89
Q
A

1,25-Hydroxyvitamin D3

90
Q

What is vitamin D3?

A

Precursor to the biologically active form of vitamin D

91
Q

What are eicosanoids derived from?

A

Arachidonate

92
Q

Eicosanoids are released from ___ by ___.

A

Membranes, phospholipases

93
Q

What are eicosanoids modified by?

A

Mitochondrial enzymes

94
Q

What are the 4 major classes of eicosanoids?

A
  1. Prostaglandins
  2. Prostacyclins
  3. Thromboxanes
  4. Leukotrienes
95
Q

What are the local effects of prostaglandins?

A
  • Regulating blood flow
  • Stimulating inflammation
  • Controlling ion transport
  • Initiating contractions during birth
96
Q

What are prostacyclins?

A

Eicosanoid derived from prostaglandin H2 that regulates platelet aggregation and blood clotting

97
Q

What are NSAIDS?

A

Inhibitor of prostaglandin H2 that is used to reduce inflammation

98
Q

Compare and contrast COX-1 and COX-2.

A
  • Related in terms of overall 3D structure and similar catalytic activities
  • COX-1: constitutively expressed; involved in producing prostaglandins that stimulate mucin secretion and protect the stomach lining from low pH
  • COX-2: specifically expressed; responsible for producing prostaglandins that cause inflammation
99
Q

What causes the side effects of NSAIDs like stomach bleeding?

A

COX-2 is the relevant biological target, but NSAIDs inhibit both COX-1 and COX-2 so the stomach isn’t protected from low pH

100
Q

What transports TAGs synthesized in the liver?

A

VLDL particles

101
Q

What transports TAGs stored in adipose tissue?

102
Q

What are the steps of the absorption and transport of dietary TAGs?

A
  1. Emulsification of triacylglycerols by bile acids
  2. Hydrolysis of TAGs by intestinal lipases to generate free fatty acids
  3. Resynthesis of TAGs inside intestinal epithelial cells
  4. Packaging of TAGs into chylomicrons
  5. Export of chylomicrons into lymphatic system
  6. Entry if chylomicrons into circulatory system
103
Q

Diagram the conversion of 7-dehydrocholesterol to 1,25-hydroxyvitamin D

104
Q

When are fatty acids released? (At rest vs. exercise)

A

During exercise

Biochem 2 (CHEM 441B) (23 decks)

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