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Biochemistry-Block 2 CC > Metabolism of Complex Lipids > Flashcards

Metabolism of Complex Lipids Flashcards

1
Q

These molecules are a diverse and ubiquitous group of organic compounds that are insoluble in water but soluble in organic solvents.

A

Lipids

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2
Q

Name some lipids that display lipid classifications (insoluble in water but soluble in organic solvents).

A

Fatty Acids, TAG, phospholipids, Sterols, Sphingolipids, Terpenes

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3
Q

Lipids are a extemely heterogeneous collection of molecules from a ____ and ____ standpoint.

A

structural and functional

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4
Q

True/False: There are few differences with regard to scope and organization of current classification schemes.

A

False; significant differences

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5
Q

Name the two types of phospholipids

A

Glycerophospholipids and Sphingophospholipids

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6
Q

Describe the features of Amphipatic molescules

A

Hydrophilic Head, Hydrophobic Tails

In water, the:
-Hydrophilic heads OUT
-Hydrophobic tails IN
to form lipid bilayer

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7
Q

_______ serve as the major structural component of all biological membranes.

A

Phospholipids (due to hydrophilic hradsand hydrophobic tails)

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8
Q

Within the membranes, phospholipids function as:

A
  • reservoir for intracellular second messengers

- anchor point for membrane proteins

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9
Q

Phospholipids serves as a component of:

A
  • Lipoprotein particles
  • Pulmonary surfactants
  • Bile
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10
Q

Where is Bile produced?

A

Hepatocytes

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11
Q

Name the lipoprotein particles:

A

chylomicrons, VLDL, LDL, HDL

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12
Q

What secretes pulmonary surfactants?

A

alveolar epithelial cells

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13
Q

What Glycerophospholipid influences Membrane curvature and vesicle formation?

A

Phosphatidic Acid (PA)

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14
Q

____ is a precursor for the synthesis of all other glycerphospholipids and TAG

A

Phosphatidic Acid (PA)

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15
Q

This glycerophospholipid is a signaling molecule.

A

Phosphatidic Acid (PA)

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16
Q

What makes up Phosphatidylcholine (PC)?

A

PC = PA + choline

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17
Q

Name the most abundant phospholipid.

A

Phosphatidylcholine (PC, lecithin)

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18
Q

Phosphatidylcholine (PC, lecithin) is a major component of ____

A

lung surfactant (as dipalmitoyl lecithin or DPPC)

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19
Q

Phosphatidylcholine (PC, lecithin) serves as a storage for ____

A

choline (essential dietary nutrient)

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20
Q

____ is a complex mixture of 90% lipids and 10% proteins

A

Lung (pulmonary) surfactant

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21
Q

What are the roles of the Lung (Pulmonary) Surfactant?

A
  • decreases surface tension of extracellular fluid layer covering alveoli
  • reduces pressure needed to reinflate alveoli
  • prevents alveolar collapse (atelectasis)
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22
Q

This is due to insufficient lung surfactant (production and/or secretion) and is the significant cause of all neonatal deaths in Western countries.
Occurs in preterm infants.

A

Respiratory Distress Syndrome (RSD)

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23
Q

What makes up Phosphatidylethanolamine (PE, cephalin)?

A

PE = PA + ethanolamine

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24
Q

This is the second most abundant phospholipid.

A

Phosphatidylethanolamine (PE, cephalin)

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25
Q

Phosphatidylethanolamine (PE, cephalin) is used for the synthesis of

A

phosphatidylserine in exchange reaction with free serine

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26
Q

What makes up Phosphatidylserine (PS)

A

PS = PA + Serine

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27
Q

This phospholipid is less abundant than PC and PE, only found in the inner leaflet of the plasma membrane.

A

Phosphatidylserine (PS)

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28
Q

Phosphatidylserine (PS) is required for

A

membrane synthesis

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29
Q

Phosphatidylserine (PS) plays a role in

A

recognition of apoptotic cells

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30
Q

Phosphatidylinositols (Pls) is made of

A

Pl = PA + inositol

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31
Q

Phosphatidylinositols (Pls) is an unusual lipid because

A

it contains stearic acid at C1 and ARACHIDONIC ACID at C2

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32
Q

Phosphatidylinositols (Pls) serves as a reservoir for

A

arachidonic acid making it a precursor for prostaglandins

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33
Q

In Phosphatidylinositols (Pls), ____ groups can be phosphorylated producing important precursor for second messenger molecules: ___.

A

-OH; PIP2

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34
Q

PIP2 is a substrate for ___ in order to produce ____ and ___.

A

PLC; IP3 and DAG

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35
Q

What are IP3 and DAG?

A

Second messenger molecules that play roles in cell signaling cascades.

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36
Q

Phosphatidylinositols (Pls) serve as

A

anchor points for proteins

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37
Q

What makes up Phosphatidylglycerol (PG)?

A

PG = PA + glycerol

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38
Q

____ is a precursor of surfactant and its presence (>0.3) in the amniotic fluid indicates fetal lung maturity.

A

Phosphatidylglycerol (PG)

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39
Q

Phosphatidylglycerol (PG) is a precursor for the

A

synthesis of cardiolipin

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40
Q

Cardiolipin (disphosphatidylglycerol) is exclusive to the

A

inner mitochondrial membrane

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41
Q

Cardiolipin (disphosphatidylglycerol) maintains the

A

structure and function of ETC complexes

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42
Q

_________ are 2 PA molecules esterified through their phosphate groups

A

Cardiolipin (disphosphatidylglycerol)

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43
Q

For ____ ___________, the FA at C-1 is attached via ether linkages (not ester)

A

Ether glycerophosphospholipids

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44
Q

Name the two types of Ether glycerophosphospholipids that are based on the saturation of the FA attached at C1

A

Plamalogens

Platelet-Activating Factor (PAF)

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45
Q

Name the two types of Plasmalogens

A
  1. Phosphatidalcholine (in heart muscle)

2. Phosphatidalethanolamine (in nerve tissue)

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46
Q

______ are unsaturated FA at C1

A

Plasmalogens

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47
Q

______–saturated FA at C-1 and a short acetyl group at C-2 rather than acyl

A

Platelet-Activating Factor (PAF)

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48
Q

______:

  • are synthesized and released by variety of cell types
  • one of the most potent bioactive molecules
  • Mediate anaphylaxis and hypersensitive
A

Platelet-Activating Factor (PAF)

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49
Q

How is Platelet-Activating Factor (PAF) one of the most potent bioactive molecules?

A

It triggers thrombotic and inflammatory events

50
Q

It is important to know that most lipids are synthesized in the _______

A

Smooth ER

51
Q

Where are the Ether Lipids located?

A

Peroxisomes

52
Q

Most ______ go from the smooth ER–> Golgi –> transport vesicles –> other membranes

A

lipids

53
Q

CDP-DAG pathways is used for

A

PI, PG, cardiolipin

54
Q

Describe the synthesis of PS:

  • ___ is used as a substrate for synthesis of PS
  • ________ reaction
  • _________ but primarily used to produce PS
A
  • PE is used as a substrate for synthesis of PS
  • Base exchange reaction
  • Reversible step but primarily used to produce PS
55
Q

Describe the Sythesis of PC from PS and PE in the liver:

  • _____ is decarboxylated to form PE
  • PE is ______ is 3 subsequent steps using methyl donors (SAM)
A
  • PS is decarboxyalted to form PE

- PE is methylated in 3 subsequent steps using methyl donors (SAM)

56
Q

_____ requires this secondary mechanism to produce PC even when free choline levels are low

A

Liver

57
Q

A significant amount of PC are secreted from

A

liver cells in the bile

58
Q

A significant amount of PC are incorporated into ____ and secreted

A

lipoproteins

59
Q

What is significant about Sphingomyelin?

A

It is the only sphingolipid that is also a phospholipid

60
Q

What forms Ceramide?

A

Fatty Acid + Sphingosine = Ceramide

61
Q

______ hydrolyze the phosphodiester bonds of glycerophospholipids

A

Phospholipases (PLPs)

62
Q

Phospholipases (PLPs) performs site ____ ____ –where each PLP acts on a specific bond

A

(site) specific cleavage

63
Q

Phospholipases (PLPs) release bioactive molecules that can serve as ____ ____, (DAG, IP3)

A

second messengers

64
Q

Phospholipases (PLPs) participate in the remodeling of phospholipids together with _____ ___ ___ transferases.

A

Fatty Acyl CoA transferases

65
Q

Phospholipase A2 is present in many _________ and ______, as well as snake and bee venoms.

A

mammalian tissues and pancreatic juices

66
Q

Pancreatic secretions are especially rich in Phospholipase A2 proenzyme, which is activated by _____ and requires bile salts for activity.

A

trypsin

67
Q

Phospholipase A2, acting on phosphatidylinsoitol, releases ______

A

arachidonic acid

68
Q

Phospholipase A2 is inhibited by

A

glucocorticoids (I.E. cortisol)

69
Q

Phospholipase D is involved in ____ ______, generated phosphatidic acid (PA) from phosphatidulchone and diacylglycerol from PA

A

signal transduction

70
Q

______ is found in liver lysosomes and the alpha-toxin of clostridia and other bacilli

A

Phospholipase C

71
Q

Membrane bound _________ is activated by the PIP2 system and thus plays a role in producing second messengers

A

Phospholipase C

72
Q

Phospholipase A1 is present in many _______

A

mammalian tissues

73
Q

_____ is the prodominant sphingophospholipid in mammalian cells

A

Sphingomyelin (SM)

74
Q

______ is the major structural sphingolipid in the plasma membrane

A

Sphingomyelin (SM)

75
Q

As a major structural sphingolipid in the plasma membrane, Sphingomyelin plays a role in ________ and ____________

A

lipid raft formation and signaling as prescursor for the bioactive ceramide

76
Q

Sphingomyelin (SM) is abundant in _____ _____.

A

nerve tissue (membranes and constituent of myelin sheath)

77
Q

Ceramides (Cer) are a diverse group of molecules that differ in the _______ attached to the sphingosine

A

type of fatty acid

78
Q

Ceramide = _____ + ________

A

sphingosine + fatty acid

79
Q

______ is a precursor for SM and all glycosphingolipids

A

Ceramide

80
Q

Ceramide is a bioactive ______; it plays a role in cell signaling

A

second messenger

81
Q

In the skin, ceramides play a role in __________

A

maintaining the skin’s water-permeability barrier

82
Q

Decreased levels of ceramides are associated with a number of

A

skin diseases

83
Q

Sphingosine = ______ + _______

A

palmitic acid + serine

84
Q

Sphingosine is a ____________ molecule

A

bioactive second messenger

85
Q

Sphingosine is a precursor for __________

A

sphingosine 1-phosphate

86
Q

sphingosine 1-phosphate is a potent _____ recognized by atleast 5 different GPCR

A

bioactive 2nd messenger

87
Q

_________ play a role in the regulation of cellular interactions and growth/development

A

Glycosphingolipids (GSLs)

88
Q

Transformed cells dramatically change their plasma membrane _______ composition

A

glycosphingolipid

89
Q

______:

-source of blood group antigens

A

Antigens

90
Q

_______:

-function as antigens in embryonic development

A

antigenic

91
Q

_____ serve as cell surface receptors for cholera and tetanus toxins, certain viruses and microbes

A

Antigenic

92
Q

The ____ portion of a glycolipid is the antigenic determinant

A

carbohydrate

93
Q

______ are neutral GSLs

A

Cerebrosides

94
Q

Cerebroside = ______ + ______

A

Ceramide + sugar

95
Q

Name 3 types of Cerebrosides

A

1) Galactosylceramide
2) Glucosylceramide
3) Lactosylceramide

96
Q

____ is an essential component of membranes, mostly found on the outer leaflet of the plasma membrane

A

Cerebrosides

97
Q

______ participate in lipid raft formation and are predominant in nerve tissue (brain and periphery)

A

Cerebrosides

98
Q

______ - negatively charged at pH 7

A

Acidic GSLs

99
Q

Gangliosides = _____ + ______ + ____

A

Cer + oligosaccharide + NANA

100
Q

_______ are found primarily in the ganglion cells in the CNS

A

Gangliosides

101
Q

______ are medically important because several lipid storage disorders lead to accumulation of these lipids

A

Gangliosides

102
Q

_______ = Galactocerebroside + -SO3- group

A

Sulfatides

103
Q

Sulfatides are found in the ____ and _____

A

brain and kidney

104
Q

Sphingolipid Synthesis begins in the ____ with the condensation of palmitoyl CoA and L-serine.

A

ER

105
Q

The 1st step of Sphingolipid Synthesis, the condensation of Palmitoyl CoA and L-serine is catalyzed by

A

Serine Palmitoyl Transferase (SPT)

106
Q

The 1st step of Sphingolipid Synthesis, the condensation of Palmitoyl CoA and L-serine is catalyzed by Serine Palmitoyl Transferase (SPT) requires _____ as a coenzyme

A

PLP

107
Q

What is significance of the 1st step of Sphingolipid Synthesis, the condensation of Palmitoyl CoA and L-serine?

A

It is the rate-limiting step

108
Q

_____ is transferred to the Golgi where it is used as a substrate for the synthesis of Sphingomyelin and Glycosphingolipids.

A

Ceramide

109
Q

From the golgi, SM and GSLs are distributed to all membranes via vesicular transport or incorporated and secreted into _______ (liver, gut)

A

lipoproteins

110
Q

Local (limited) degradation of SM in the plasma membrane by Neutral Sphingomyelinases produces ________ that plays a role in cell signaling events

A

ceramide

111
Q

Complete degradation of SM and GSLs internalized via endocytotic pathways occurs in the ______ by different acidic enzymes with optimal pH ~4.5

A

lysosomes

112
Q

Deficiency in any of these enzymes results in particular lysosomal lipid storage disease under the common name of _________

(Sphingomyelinase, Cermidase, alpha- and beta-galactosidase, Beta-hezosaminase A and B, Arylsulfatase A)

A

sphingolipidoses

113
Q

In a healthy state sphingolipid synthesis and degradation are balanced tightly, so the amount of these compounds are at ______

A

constant levels

114
Q

If a particular acid hydrolase is defective or totally missing, the respective SL substrate _______

A

accumulates

115
Q

The disorders are progessive and affect predominantly ______ because of the high abundance of SLs.

A

Nervous Tissue

116
Q

Most sphingolipidoses are __________ (except for Fabry disease, which is X-linked)

A

autosomal recessive diseases

117
Q

Depending on the severity of the mutation, they may be fatal is early life or may have extensive _________ variability

A

phenotypic

118
Q

______ variability is also seen because a given disorder can be caused by any one of a variety of mutations within a single gene

A

Genetic Variability

119
Q

The incidence of sphingolipidoses is _______ in most populations

A

low

120
Q

Exceptions are the ______, _____ and _______ diseases which are more frequent in the Ashkenazi Jewish Population

A

Gaucher, Tay-Sachs and Niemann-Pick

Biochemistry-Block 2 CC (13 decks)

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