Metabolism of Complex Lipids Flashcards
(120 cards)
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
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
3
Q
Lipids are a extemely heterogeneous collection of molecules from a ____ and ____ standpoint.
A
structural and functional
4
Q
True/False: There are few differences with regard to scope and organization of current classification schemes.
A
False; significant differences
5
Q
Name the two types of phospholipids
A
Glycerophospholipids and Sphingophospholipids
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
7
Q
_______ serve as the major structural component of all biological membranes.
A
Phospholipids (due to hydrophilic hradsand hydrophobic tails)
8
Q
Within the membranes, phospholipids function as:
A
- reservoir for intracellular second messengers
- anchor point for membrane proteins
9
Q
Phospholipids serves as a component of:
A
- Lipoprotein particles
- Pulmonary surfactants
- Bile
10
Q
Where is Bile produced?
A
Hepatocytes
11
Q
Name the lipoprotein particles:
A
chylomicrons, VLDL, LDL, HDL
12
Q
What secretes pulmonary surfactants?
A
alveolar epithelial cells
13
Q
What Glycerophospholipid influences Membrane curvature and vesicle formation?
A
Phosphatidic Acid (PA)
14
Q
____ is a precursor for the synthesis of all other glycerphospholipids and TAG
A
Phosphatidic Acid (PA)
15
Q
This glycerophospholipid is a signaling molecule.
A
Phosphatidic Acid (PA)
16
Q
What makes up Phosphatidylcholine (PC)?
A
PC = PA + choline
17
Q
Name the most abundant phospholipid.
A
Phosphatidylcholine (PC, lecithin)
18
Q
Phosphatidylcholine (PC, lecithin) is a major component of ____
A
lung surfactant (as dipalmitoyl lecithin or DPPC)
19
Q
Phosphatidylcholine (PC, lecithin) serves as a storage for ____
A
choline (essential dietary nutrient)
20
Q
____ is a complex mixture of 90% lipids and 10% proteins
A
Lung (pulmonary) surfactant
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)
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)
23
Q
What makes up Phosphatidylethanolamine (PE, cephalin)?
A
PE = PA + ethanolamine
24
Q
This is the second most abundant phospholipid.
A
Phosphatidylethanolamine (PE, cephalin)
25
Phosphatidylethanolamine (PE, cephalin) is used for the synthesis of
phosphatidylserine in exchange reaction with free serine
26
What makes up Phosphatidylserine (PS)
PS = PA + Serine
27
This phospholipid is less abundant than PC and PE, only found in the inner leaflet of the plasma membrane.
Phosphatidylserine (PS)
28
Phosphatidylserine (PS) is required for
membrane synthesis
29
Phosphatidylserine (PS) plays a role in
recognition of apoptotic cells
30
Phosphatidylinositols (Pls) is made of
Pl = PA + inositol
31
Phosphatidylinositols (Pls) is an unusual lipid because
it contains stearic acid at C1 and ARACHIDONIC ACID at C2
32
Phosphatidylinositols (Pls) serves as a reservoir for
arachidonic acid making it a precursor for prostaglandins
33
In Phosphatidylinositols (Pls), ____ groups can be phosphorylated producing important precursor for second messenger molecules: ___.
-OH; PIP2
34
PIP2 is a substrate for ___ in order to produce ____ and ___.
PLC; IP3 and DAG
35
What are IP3 and DAG?
Second messenger molecules that play roles in cell signaling cascades.
36
Phosphatidylinositols (Pls) serve as
anchor points for proteins
37
What makes up Phosphatidylglycerol (PG)?
PG = PA + glycerol
38
____ is a precursor of surfactant and its presence (>0.3) in the amniotic fluid indicates fetal lung maturity.
Phosphatidylglycerol (PG)
39
Phosphatidylglycerol (PG) is a precursor for the
synthesis of cardiolipin
40
Cardiolipin (disphosphatidylglycerol) is exclusive to the
inner mitochondrial membrane
41
Cardiolipin (disphosphatidylglycerol) maintains the
structure and function of ETC complexes
42
_________ are 2 PA molecules esterified through their phosphate groups
Cardiolipin (disphosphatidylglycerol)
43
For ____ ___________, the FA at C-1 is attached via ether linkages (not ester)
Ether glycerophosphospholipids
44
Name the two types of Ether glycerophosphospholipids that are based on the saturation of the FA attached at C1
Plamalogens
| Platelet-Activating Factor (PAF)
45
Name the two types of Plasmalogens
1. Phosphatidalcholine (in heart muscle)
| 2. Phosphatidalethanolamine (in nerve tissue)
46
______ are unsaturated FA at C1
Plasmalogens
47
______--saturated FA at C-1 and a short acetyl group at C-2 rather than acyl
Platelet-Activating Factor (PAF)
48
______:
- are synthesized and released by variety of cell types
- one of the most potent bioactive molecules
- Mediate anaphylaxis and hypersensitive
Platelet-Activating Factor (PAF)
49
How is Platelet-Activating Factor (PAF) one of the most potent bioactive molecules?
It triggers thrombotic and inflammatory events
50
It is important to know that most lipids are synthesized in the _______
Smooth ER
51
Where are the Ether Lipids located?
Peroxisomes
52
Most ______ go from the smooth ER--> Golgi --> transport vesicles --> other membranes
lipids
53
CDP-DAG pathways is used for
PI, PG, cardiolipin
54
Describe the synthesis of PS:
- ___ is used as a substrate for synthesis of PS
- ________ reaction
- _________ but primarily used to produce PS
- PE is used as a substrate for synthesis of PS
- Base exchange reaction
- Reversible step but primarily used to produce PS
55
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)
- PS is decarboxyalted to form PE
| - PE is methylated in 3 subsequent steps using methyl donors (SAM)
56
_____ requires this secondary mechanism to produce PC even when free choline levels are low
Liver
57
A significant amount of PC are secreted from
liver cells in the bile
58
A significant amount of PC are incorporated into ____ and secreted
lipoproteins
59
What is significant about Sphingomyelin?
It is the only sphingolipid that is also a phospholipid
60
What forms Ceramide?
Fatty Acid + Sphingosine = Ceramide
61
______ hydrolyze the phosphodiester bonds of glycerophospholipids
Phospholipases (PLPs)
62
Phospholipases (PLPs) performs site ____ ____ --where each PLP acts on a specific bond
(site) specific cleavage
63
Phospholipases (PLPs) release bioactive molecules that can serve as ____ ____, (DAG, IP3)
second messengers
64
Phospholipases (PLPs) participate in the remodeling of phospholipids together with _____ ___ ___ transferases.
Fatty Acyl CoA transferases
65
Phospholipase A2 is present in many _________ and ______, as well as snake and bee venoms.
mammalian tissues and pancreatic juices
66
Pancreatic secretions are especially rich in Phospholipase A2 proenzyme, which is activated by _____ and requires bile salts for activity.
trypsin
67
Phospholipase A2, acting on phosphatidylinsoitol, releases ______
arachidonic acid
68
Phospholipase A2 is inhibited by
glucocorticoids (I.E. cortisol)
69
Phospholipase D is involved in ____ ______, generated phosphatidic acid (PA) from phosphatidulchone and diacylglycerol from PA
signal transduction
70
______ is found in liver lysosomes and the alpha-toxin of clostridia and other bacilli
Phospholipase C
71
Membrane bound _________ is activated by the PIP2 system and thus plays a role in producing second messengers
Phospholipase C
72
Phospholipase A1 is present in many _______
mammalian tissues
73
_____ is the prodominant sphingophospholipid in mammalian cells
Sphingomyelin (SM)
74
______ is the major structural sphingolipid in the plasma membrane
Sphingomyelin (SM)
75
As a major structural sphingolipid in the plasma membrane, Sphingomyelin plays a role in ________ and ____________
lipid raft formation and signaling as prescursor for the bioactive ceramide
76
Sphingomyelin (SM) is abundant in _____ _____.
nerve tissue (membranes and constituent of myelin sheath)
77
Ceramides (Cer) are a diverse group of molecules that differ in the _______ attached to the sphingosine
type of fatty acid
78
Ceramide = _____ + ________
sphingosine + fatty acid
79
______ is a precursor for SM and all glycosphingolipids
Ceramide
80
Ceramide is a bioactive ______; it plays a role in cell signaling
second messenger
81
In the skin, ceramides play a role in __________
maintaining the skin's water-permeability barrier
82
Decreased levels of ceramides are associated with a number of
skin diseases
83
Sphingosine = ______ + _______
palmitic acid + serine
84
Sphingosine is a ____________ molecule
bioactive second messenger
85
Sphingosine is a precursor for __________
sphingosine 1-phosphate
86
sphingosine 1-phosphate is a potent _____ recognized by atleast 5 different GPCR
bioactive 2nd messenger
87
_________ play a role in the regulation of cellular interactions and growth/development
Glycosphingolipids (GSLs)
88
Transformed cells dramatically change their plasma membrane _______ composition
glycosphingolipid
89
______:
| -source of blood group antigens
Antigens
90
_______:
| -function as antigens in embryonic development
antigenic
91
_____ serve as cell surface receptors for cholera and tetanus toxins, certain viruses and microbes
Antigenic
92
The ____ portion of a glycolipid is the antigenic determinant
carbohydrate
93
______ are neutral GSLs
Cerebrosides
94
Cerebroside = ______ + ______
Ceramide + sugar
95
Name 3 types of Cerebrosides
1) Galactosylceramide
2) Glucosylceramide
3) Lactosylceramide
96
____ is an essential component of membranes, mostly found on the outer leaflet of the plasma membrane
Cerebrosides
97
______ participate in lipid raft formation and are predominant in nerve tissue (brain and periphery)
Cerebrosides
98
______ - negatively charged at pH 7
Acidic GSLs
99
Gangliosides = _____ + ______ + ____
Cer + oligosaccharide + NANA
100
_______ are found primarily in the ganglion cells in the CNS
Gangliosides
101
______ are medically important because several lipid storage disorders lead to accumulation of these lipids
Gangliosides
102
_______ = Galactocerebroside + -SO3- group
Sulfatides
103
Sulfatides are found in the ____ and _____
brain and kidney
104
Sphingolipid Synthesis begins in the ____ with the condensation of palmitoyl CoA and L-serine.
ER
105
The 1st step of Sphingolipid Synthesis, the condensation of Palmitoyl CoA and L-serine is catalyzed by
Serine Palmitoyl Transferase (SPT)
106
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
PLP
107
What is significance of the 1st step of Sphingolipid Synthesis, the condensation of Palmitoyl CoA and L-serine?
It is the rate-limiting step
108
_____ is transferred to the Golgi where it is used as a substrate for the synthesis of Sphingomyelin and Glycosphingolipids.
Ceramide
109
From the golgi, SM and GSLs are distributed to all membranes via vesicular transport or incorporated and secreted into _______ (liver, gut)
lipoproteins
110
Local (limited) degradation of SM in the plasma membrane by Neutral Sphingomyelinases produces ________ that plays a role in cell signaling events
ceramide
111
Complete degradation of SM and GSLs internalized via endocytotic pathways occurs in the ______ by different acidic enzymes with optimal pH ~4.5
lysosomes
112
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)
sphingolipidoses
113
In a healthy state sphingolipid synthesis and degradation are balanced tightly, so the amount of these compounds are at ______
constant levels
114
If a particular acid hydrolase is defective or totally missing, the respective SL substrate _______
accumulates
115
The disorders are progessive and affect predominantly ______ because of the high abundance of SLs.
Nervous Tissue
116
Most sphingolipidoses are __________ (except for Fabry disease, which is X-linked)
autosomal recessive diseases
117
Depending on the severity of the mutation, they may be fatal is early life or may have extensive _________ variability
phenotypic
118
______ variability is also seen because a given disorder can be caused by any one of a variety of mutations within a single gene
Genetic Variability
119
The incidence of sphingolipidoses is _______ in most populations
low
120
Exceptions are the ______, _____ and _______ diseases which are more frequent in the Ashkenazi Jewish Population
Gaucher, Tay-Sachs and Niemann-Pick
