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Lipids Flashcards

1
Q

Defined as biosynthesis of fatty acid

A

Lipogenesis

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2
Q

Three types of lipogenic pathways based on cellular localization

A

Extramitochondrial
Microsomal
Mitochondrial

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3
Q

Extramitochondrial lipogenesis pathway occurs in

A

Cytosol

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4
Q

Microsomal lipogenesis pathway occurs in

A

Smooth endoplasmic reticulum

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5
Q

Mitochondrial lipogenesis pathway occurs in

A

Mitochondrion

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6
Q

General principle of lipogenesis is

A

Add 2 carbon atoms per cycle

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7
Q

Takes place in the cytosol

Conversion of acetyl CoA to malonyl CoA via acetyl CoA carboxylase is the rate limiting step

Uses biotin

A

Extramitochondrial lipogenesis

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8
Q

In the extramitochondrial lipogenesis pathway, Acetyl CoA is converted to

*rate-limiting step

A

malonyl CoA

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9
Q

Is the rate-limiting step or committed enzyme in extramitochondrial lipogenesis

A

Acetyl CoA Carboxylase

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10
Q

Prosthetic group of Acetyl CoA

A

Biotin

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11
Q

Acetyl CoA carboxylase for conversion of acetyl coa to malonyl coa is inhibited by

A

palmitic acid

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12
Q

A protein found in raw egg white, inhibits the committed step by binding and removing biotin

A

Avidin to acetyl carboxylase

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13
Q

Energy source per gram of lipid

A

9 calories

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14
Q

Adipose ->

A

Fatty acids -> CO2 + H2O + ATP

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15
Q

Major components of cell membranes

A

Phosphoglycerides
Sphingolipids
Cholesterol

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16
Q

Lipid classes

A 
Fatty acid derivatives
Triacylglycerol (TAG)
Phospholipids
Sphingolipids
Wax esters
Isoprenoids (terpenes, steroids)
Lipoproteins
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17
Q

2-4 carbon atom Fatty acids

A

Short

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18
Q

6-10 carbon atom fatty acid

A

Medium

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19
Q

12-26 carbon atom or more fatty acid

A

Long

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20
Q

Have only single bonds in hydrocarbon chain

A

Saturated fatty acid

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21
Q

Are solids at room temperature because the regular nature of their aliphatic chains allows the molecules to be packed in close, parallel alignment

Have only single bonds in hydrocarbon chain

A

Saturated fatty acids

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22
Q

Have at least one C = C double bond in the chains

In contrast, are all liquid at room temperature because the cis double bonds interrupt the packing of the chains

Thus less energy is required to melt them

A

Unsaturated fatty acids

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23
Q

The greater the degree of unsaturation,

A

the lower the melting point

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24
Q

20 Carbon Double-Bonds with Methyl, Oil soluble OMEGA end and a Carboxyl, Water-soluble Delta End

A 
Eicosapenaenoic acid (EPA)
Omega 3
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25
Q

22 Carbon Double-Bonds with Methyl, Oil-soluble, Omega End and Carboxyl, Water-Soluble Delta End

A 
Docasahexaenoic Acid (DHA) 
Omega 3
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26
Q

18 Carbon Double-Bonds with Methyl, Oil-soluble Omega end and Carboxyl, Water-Soluble Delta end

A

Gamma-linolenic Acid (GLA)

Omega 6

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27
Q

20 Carbon Double-bonds with Methyl, Oil-Soluble Omega End and Carboxyl, Water-Soluble Delta End

A

Dihomo-gamma-linolenic Acid (DGLA)

Omega 6

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28
Q

Polyunsaturated >2 double bonds
Not synthesized by body
Decrease risk of Cardiovascular Disease
Polyenoic fatty acids

A

Essential fatty acids

Omega 3
Omega 6

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29
Q

C18 having two double bonds

A

Linoleic acid

Lady linoleic linolenic

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30
Q

C18 having three

Precursor of EPA (eicosapentaenoic acid) and DHA (docosahexanoic acid)

A

Linolenic acid

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31
Q

C20 having four double bonds

A

Arachidonic acid

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32
Q

The main storage forms of fatty acids

The acylglycerols are esters of fatty acids bound to the sugar alcohol glycerol

All three OH groups of glycerol are esterified

They are the most common lipid material

A

TAG

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33
Q

They are also called neutral fats, because the carboxyl groups of the fatty acids are bound in ester linkage and can no longer function as acids

Mixtures are referred to as fats or oils

A

TAG

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34
Q

Molecules are classified according to which alcohol becomes esterified to the phosphate group

A

Phosphoglyceride

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35
Q 
Phosphatidylcholine (PC or Lecithin)
Phosphatidylethanolamine 
Phosphatidylserine 
Diphosphatidylglycerol
Phosphatidylinositol
A

Phosphoglyceride

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36
Q

Surfactants or surface-acting agents

Plays an essential role in reducing surface tension in lung alveoli

Increase pulmonary compliance

Respiratory Distress Syndrome of the newborn

A

Lecithin

Phosphatidylcholine

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37
Q

Serologic test for syphilis

Utilizes a diphosphatidylglycerol as the antigen

A

Venereal Disease Research Laboratory

Cardiolipin

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38
Q

With repeating 5-carbon units (isoprene)

Terpenes
Steroids

A

Isoprenoids

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39
Q

Mixed terpenoids

A 
Vitamin E (alpha tocopherol)
Ubiquinone
Vitamin K
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40
Q

Complex derivatives of triterpenes

All with 4 fused rings

The essential structural nucleus of the steroids consists of three fused cyclohexane rings joined to a cyclyopentene ring

A

Steroids

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41
Q

Ovarian steroid

A

estrogen

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42
Q

18 Carbon atoms

The A ring of the steroid nucleus of estrogen is aromatic

A

Estrogen

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43
Q

Has OH groups attached to carbons 3 and 17

A

Estradiol

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44
Q

Produced in the adrenal cortex and the testes

19 Carbon atoms

Testosterone
Dehydroepiandrosterone

A

Androgens

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45
Q

One of the more potent androgen

A

Testosterone

46
Q

Unlike testosterone is a 17-ketosteroid

A

Dehydroepiandrosterone (DHA)

47
Q

Synthesized in the corpus luteum

Has 21 carbons

A

Progesterone

48
Q

A potent glucocorticoid with weak mineralocorticoid activity

49
Q

Is a potent mineralocorticoid but a weak glucocorticoid

A

Aldosterone

50
Q

This assay detects all 21-carbon steroids with a 17-OH group, such as cortisol

A

Urinary 17-hydroxycorticosteroid

51
Q

Lipids must bind to proteins to make them water-soluble for transport in the blood

A

Lipoproteins

52
Q

Are the least dense lipoproteins

After a fatty meal, the blood appears milky due to the high concentration of chylomicrons

A

Chlyomicrons

53
Q

An anticoagulant also helps to clear chylomicrons from the blood, perhaps by stimulating lipoprotein lipase

54
Q

The inherited absence of lipoprotein lipase causes

A

Hyperchlyomicronemia

Frederickson’s type I hyperlipoproteinemia

55
Q

Contain principally triglycerides, but have a greater protein, phospholipid, and cholesterol content than chylomicrons

Their protein and phospholipid content makes them charged so that they migrate just before the B-globulins in electrophoresis hence they are termed pre-B lipoproteins

A

Very low-density lipoproteins (VLDL)

56
Q

Is synthesized in the liver

This fraction is markedly elevated in type IV hyperlipoproteinemia

57
Q

Contain mainly cholesterol in contrast to the content of chylomicrons and VLDL

58
Q

They migrate together with B-globulins

They are termed B-lipoproteins

59
Q

The fraction is markedly elevated in Type II Hyperlipoproteinemia and is associated with a high incidence of atherosclerosis

60
Q

Contain mainly protein and phospholipid

They contain significant amounts of cholesterol but have little triglyceride

A

High density lipoproteins HDL

61
Q

The high protein, low triglyceride content makes them very dense

They are termed alpha-Lipoproteins

A

High density lipoprotein HDL

62
Q

3 main classes of lipids are found in biological membranes:

A

Phospholipid
Glycolipid
Cholesterol

63
Q

Lipid bilayer is

A

amphipathic

64
Q

“Water-loving” polar head group

A

Hydrophilic

65
Q

“Water-hating” non-polar tails

A

Hydrophobic

66
Q

Inherited disorder characterized by significant reduced levels of high-density lipoproteins in the blood

Orange tonsils
Hepatomegaly
Neuropathy (mononeuritis simplex)
Low or absent HDL-C
Premature CV disease
A

Tangiers disease

Familial Alpha Lipoprotein Deficiency

67
Q

Tangiers disease results from a mutation of a transmembrane protein that transports phospholipid & cholesterol out of the liver to generate HDL

68
Q

Functions of lipid

A

As energy source 9kcal/gram
Protein sparer
Facilitates absorption of fat soluble vitamins

69
Q

The only absolute essential fatty acid (EFA)

Precursor of arachidonic acid

A

Linoleic acid

70
Q

FA that reduces risk of heart disease

71
Q

FA that potentially significantly improves autism

A

Docosahexanoic acid

Omega 3

72
Q

Extramitochondrial lipogenesis

Sources of NADPH

A

HMP shunt

Malic enzyme reaction (Malate -> Pyruvate)

73
Q

Rate limiting step of extramitochondrial lipogenesis

by enzyme

A

Conversion of acetyl coA to malonyl coa

acetyl coa carboxylase

74
Q

18 C

soaps, shampoos, detergents, shaving creams

A

Stearic acid

75
Q

16 C

A

Palmitic acid

76
Q

Body can synthesize needed fat except

A

Linoleic

Alpha linolenic

77
Q

Alpha linolenic acid

A

Omega 3 FA

78
Q

Linoleic acid

A

Omega 6 FA

79
Q

Omega 3 fatty acids

A 
Alpha linolenic acid (ALA) 
Eicosapentanoic acid (EPA) 
Docohexanenoic acid (DHA)
80
Q

Nerve problem treatment

81
Q

Omega 6 Fatty acid

A

Linoleic acid

82
Q

Omega 3

A

Alpha Linolenic Acid (ALA)

then

Eicosapentaenoic acid (EPA)
Docosahexaenoic acid (DHA)
83
Q

Intestinal mucosal cells secrete nascent TG-rich

A

chylomicrons

84
Q

Liver secretes nascent TG-rich

85
Q

Neutral lipid core (triacylglycerol + cholesterol ester) surrounded by a shell of apolipoproteins, phospholipids, nonesterified cholesterol

Soluble in aqueous solution

A

Lipoprotein

86
Q

Lipoprotein with lowest density
Largest in size
Most lipid
Smallest percentage of protein

A

Chylomicron

87
Q

Chylomicron inherent apolipoprotein

88
Q

Nascent VLDL (liver) inherent apolipoprotein

89
Q

Transferred from HDL to nascent CM and VLDL

A

ApoCII

ApoE

90
Q

Activated by apoCII and degrades triacylglycerol in chylomicrons and VLDL

Found in capillaries of tissue adipose, cardiac and skeletal muscle

A

Lipoprotein lipase

91
Q

Lipoprotein lipase degrades (hydrolyzes) TAG of chylomicrons and VLDL into

A

Free fatty acid
Glycerol
Monoacylglycerol

and be sent back to Liver

92
Q

Most electrophoretic mobile lipoprotein

A

Chylomicron

93
Q

Least electrophoretically mobile lipoprotein

94
Q

Deficiency of lipoprotein lipase or apo-CII

Dramatic accumulation of triacylglycerol rich lipoproteins in plasma

A

Type I Hyperlipidemia

Familial hyperchylomicronemia

95
Q

C apolipoproteins after activation of lipoprotein lipase are returned to

96
Q

The cholesterol released from chylomicron regulates the

A

Rate of de novo synthesis of cholesterol

Inc cholesterol from chylomicron decreases HMG Coa reductase
allosterically inhibits the enzyme

97
Q

Carries lipid produced in the liver to peripheral tissues

TAG in this lipoprotein is also degraded by lipoprotein lipase

Contains apo B100 and A-I

98
Q

Once degraded, apo C-II and apo E go back to HDL and in exchange,

A

cholesteryl ester from HDL are transferred to VLDL with concomittant TAG and phospholipid transfer from VLDL to HDL

99
Q

Transfer of cholesteryl esters from HDL to VLDL in exchange for triacylglycerol or phospholipid is accomplished by

A

cholesteryl ester transfer proteins

100
Q

In the plasma, after exchange of cholesteryl ester VLDL is transformed into

101
Q

Intermediate sized particle observed during transition from VLDL to LDL

A

Intermediate density lipoprotein

102
Q

Retain apoB100 but lose apolipoproteins for HDL
Contain less TAG than VLDL
Higher concentration of cholesterol and cholesteryl ester

Primary function is to provide cholesterol to peripheral tissues by deposition

103
Q

Deficiency of functional LDL receptors on cell surfaces causing significant elevation of LDL and cholesterol

BUT NORMAL TAG

A

Type II hyperlipidemia
Familial hyperbetalipoproteinemia

accelerates atherosclerosis

104
Q

Degrades TAG containing SHORT FATTY ACIDS

Secreted by stomach on the stomach

A

Gastric lipase

105
Q

Degrades TAG (removes fatty acid from carbon 1, 3 leaving monoacylglycerol)

Requires pancreatic colipase for stabilization

Secreted by pancreas and sent to intestines

A

Pancreatic lipase

106
Q

Degrades TAG circulating in chylomicrons of VLDL
releasing non-esterified fatty acids and glycerol

Can be released by plasma into plasma by Heparin activated apoprotein C-II

Secreted by extrahepatic tissues on the surface of epithelial cells lining capillaries

A

Lipoprotein lipase

107
Q

Degradation of stored triacylglycerol

Activated by cAMP dependent protein kinase

Secreted by adipocytes in the adipocyte cytosol

A

Hormone sensitive lipase

108
Q

Removes fatty acid from lipids taken into cells during phagocytosis

Acid pH optimum

Secreted by most tissues acts on lysosomes

A

Acid lipase

109
Q

Functions of HDL

synthesized in liver and released by exocytosis

A

circulating reservoir of apoC-II to activate lipoprotein lipase

removing free unesterified cholesterol from extrahepatic tissues and esterifying it using phosphatidylcholine:cholesterol acyl transferase (PCAT/LecithinCAT) activated by apoA-I (inc in modest alcohol intake)

transfers cholesteryl ester to VLDL and LDL in exchange for TAG

carries cholesteryl ester to liver where HDL is degraded and cholesterol released

110
Q

Decreased concentration of plasma cholesteryl ester due to deficiency in

A

PCAT

phosphatidylcholine production

111
Q

Lipoprotein is identical to LDL except it has additional apolipoprotein molecule

this slows down breakdown of blood clots that trigger heart attacks due to similarity in amino acids 80% with plasminogen

A

apolipoprotein a

Biochemistry (32 decks)

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