Mbod block 4 week 4 Flashcards
(142 cards)
3
Q
What is the goal of fatty acid synthesis?
A
To store excess glucose as fatty acids.
4
Q
What are fatty acids stored as?
A
TAG
5
Q
What are hepatic TAGs exported from the liver as?
A
VLDLs
6
Q
What complex makes palmitate?
A
The fatty acid synthetase complex
7
Q
Where does fatty acid synthesis occur?
A
In the cytosol
8
Q
What does fatty acid synthesis require?
A
Pantothenic acid, NADPH, FADH2
9
Q
What does fatty acid synthesis use?
A
Acetyl CoA and malonyl CoA.
10
Q
Where are fatty acids found?
A
In TAGS, glycerolipids, sphingolipids, cholesterol esters, lipoproteins, membranes, etc.
11
Q
What is the role of citrate from mitochondria?
A
To provide AcCoA and NADPH for fatty acid synthesis in cytosol.
12
Q
How is glucose made into fatty acid?
A
By Lipogenesis
13
Q
What are TG’s hydrolyzed by?
A
LPL (lipoprotein lipase)
14
Q
What enzymes are upregulated by insulin in fatty acid synthesis?
A
Citrate lyase; malic enzyme
15
Q
What does the malic enzyme make?
A
NADPH and pyruvate
16
Q
What are the sources of NADPH for fatty acid synthesis?
A
Pentose-P pathway and malic enzyme
17
Q
What is citrate cleaved by?
A
citrate lyase
18
Q
What is the first committed step of fatty acid synthesis?
A
Acetyl CoA is converted to Malonyl CoA.
19
Q
What is Acetyl CoA converted to Malonyl CoA by?
A
Acetyl CoA carboxylase; reqquires Biotin
20
Q
Where are all of the enzymic activities of fatty acid synthase located?
A
On a single, large, mulifunctional fatty acid synthase enzyme.
21
Q
What are the growing intermediates attached to proteins by during fatty acid synthesis?
A
Thioester bonds
22
Q
What group does the Acyl carrier protein portion of synthase have?
A
Phospho-pantetheinyl prosthetic group.
23
Q
What other groups are on the multifunctional fatty acid synthase enzyme that also attach to FA synthesis intermediates?
A
Two sulfhydryl groups
24
Q
What is a component of the -SH group for a thioester bond with malonylCoA?
A
Panthothenic acid
25
Q
What is the first step of FA synthesis?
A
Transfer of malonyl to FA synthase
26
Q
What is the second step of FA synthesis?
A
Condensation of malonyl and acyl groups
27
What is the third step of FA synthesis?
Reduction of B-ketoacyl group with NADPH
28
What is the fourth step of FA synthesis?
Dehydration forms a double bond.
29
What is the fifth step in FA synthesis?
Reduction of double bond with NADPH.
30
How many carbons are added with each repeat of the repetitive reactions of FA synthesis?
2 C
31
What is required for a new FA chain to start?
An AcCoA is required to be the acceptor of the malonyl transfer. Must make malonyl CoA from AcCoA.
32
What is the intermediate that is formed from the condensation of malonyl and an acetyl group?
A B-keto intermediate
33
What do the reduction reactions of FA synthesis need?
NADPH
34
How many ATP are needed for Palmitate synthesis?
7 ATP
35
Where is elongase found?
In the ER
36
When does elongation occur?
While the fatty acid is bound to CoA
37
What is desaturase?
An oxidase located in the ER. It inserts a double bond at the 9th carbon from the carboxyl group. Makes palmitoleate from palmitate, and oleate from stearate.
38
What do Acyl CoA desaturases in the ER contain?
FAD, cytochrome B5, and an iron-sulfur center, froming a mini electron transport chain.
39
What is linoleate used for?
It is the major source of the essential fatty acids required in the human diet. They are used for the synthesis of arachidonic acid.
41
What do glycerolipids have as a backbone?
Glycerol
42
What are triacylglycerols made of?
A glycerol backbone + 3FA
43
What are glycerophospholipids made of?
A glycerol backbone + 2FA + head group
44
What are the functions of complex lipids?
Storage of fatty acids as TAG; Component of plasma membranes; Signal transduction; Recognition
45
What are some examples of glycerophospholipids?
Phosphatidylcholline; phosphatidylethanolamine; phosphatidylserine; phosphatidylinositol bisphosphate (PIP2); phosphatidylglycerol; cardolipin
46
What hydrolyzes triacylglycerol and diacylglycerol to form 2-monoacylglycerol?
Pancreatic lipase
47
What is TG incorporated into and released into the lymphatic system?
Chylomicrons
48
What are chylomicrons primarily composed of?
TG; also contain cholesterol and phospholipids
49
Where do chylomicrons deliver FA to?
Muscle and adipose tissue
50
What is an intermediate in TG synthesis?
A Glycerophospholipid
51
What is phosphatidic acid formed from?
Glycerol-3-P
52
What enzyme is used to form a triacylglycerol from diacylglycerol?
Diglyceride acyltransferase
53
What is LPL secreted in response to?
Insulin
54
What enzyme is activated to increase lipolysis?
Hormone sensitive lipase
55
What is the role of phospholipases?
To cleave bonds in the lysosomes, cytosol and cellular membranes.
56
What glycerophospholipids are produced by the 1st mechanism used to add the head group to phosphatidic acid?
Phosphatidylcholine; phosphatidylethanolamine; phosphatidylserine
57
What glycerophospholipids are produced by the 2nd mechanism used to add the head group to phosphatidic acid?
Phosphatidylinositol; Cardiolipin; Phosphatidylglycerol
58
What is the activation process in the 1st mechanism?
The head group is activated by CTP
59
What is the activation process in the 2nd mechanism?
DAG is activated by DAG
60
What is the alternate path to form phosphatidylcholine?
Methaylation of phosphatidylethanolamine
61
Which glycerophospholipids are reversible through interconversion?
Phosphatidylethanolamine and Phosphatidylserine
62
What is Cardiolipin?
Diphosphatidylglycerol made from phosphatidylglycerol and activated phosphatidic acid CDP-DAG
63
How does Phosphatidylinositol made from CDP-DAG PI become PIP2?
After kinase phosphorylation
64
What is 90% of surfactant?
Lipid
65
What makes up 90% of the lipids of surfactant?
Phospholipid
66
What makes up 75% of the phospholipid of surfactant?
Phosphatidylcholine
67
What is required for normal lung function?
Surfactant
68
What is the role of surfactant in normal lung function?
It reduces surface tension at the air-liquid interface and also contributes to the defense system
69
In whom is neonatal respiratory distress syndrom seen in?
Premature infants with insufficient surfactant.
70
What is the standard therapy for infants with Neonatal Respiratory Distress Syndrome?
Treating the lungs with replacement surfactant.
71
Which phospholipid peaks right before birth?
Phosphatidylcholine
72
What fatty acids are eicosanoids produced from?
Arachidonic acid
73
What are glycerolphospholipids broken down by?
Phospholipases
75
What are some head groups of glycerophospholipids?
Choline, ethanolamine, serine, inositol, glycerol
76
What are some examples of ether glycerolipids?
Plasmalogens and Platelet Activating Factor
77
How are complex lipids distributed in a plasma membrane?
Assymetricly
78
What are plasmalogens?
A major class of mitochondrial lipids. Enriched in myelin and muscle.
79
What is a platelet activating factor (PAF)?
It is released from phagocytic blood cells in response to stimuli; causes platelet aggregation, edema, and hypotension.
80
What is the ether lipid structure of plasmalogen?
Glycerol with an ether bon to a hydrocarbon tail (long chain alcohol), FA, and head group.
81
How is a PAF differend from a plasmalogen?
It has a 2-acetyl and 1-saturated fatty acid
82
What is the 2-fatty acid replaced by in PAF?
An acetyl group
83
What does the synthesis of ether glycerolipis require?
NADPH, AcylCoA, DHAP, and activated ethanolamine.
84
What is an example of a sphingophospholipid?
Sphingomyelin
85
What are some examples of glycolipids?
Cerebrosides, Sulfatides, Globosides, Gangliosides
86
What head group do sphingophospholipids have?
A P-choline group
87
What head group do glycolipids have?
A carbohydrate group
88
What is a ceramide?
A Sphingolipid that is a sphingosine+FA which forms the backbone of all other classes of sphingolipids.
89
What type of link does a ceramide have?
An amide link
90
What does ceramide synthesis start with?
Palmitoyl CoA and Serine
91
What is the reduced form of sphingosine?
dihydrosphingosine
92
What are glycolipids?
A component of cell membranes; a ceraminde backbone with carbohydrate groups attached.
93
What determines which glycolipid is formed?
The nature of the carbohydrate
94
What makes a ceramide a sphingomyelin in membranes?
An attached phosphocholine
95
What is mucolipidosis?
The inability to degrade glycolipids and sphingomyelin in membranes.
96
Which diseases are associated with mucolipidosis?
Gaucher's, Tay-Sachs, Fabray's
97
Where are glycolipids predominantly found?
In neural cell types
98
What is a neutral glycolipid?
Contains one or more sugars.
99
What are some examples of neutral glycolipids?
galactocerebrosides, glucocerebrosides; lactosyl-ceramide
100
What is an acidic glycolipid?
It is negatively charged at physiological pH; contains N-acetylneuraminic acid (NANA) or sulfate
101
What are some examples of acidic glycolipids?
Sulfatides, gangliosides
102
Where does the synthesis of glycolipids occur?
In the ER and Golgi
103
How does the synthesis of glycolipids occur?
Sequentially add activated glycosyl residues; enzymes recognize specific structures
104
What is PAPS?
An activaed sulfate group that transferrs a sulfate for the formation of a sulfatide.
105
What are the multiple kinds of gangliosides?
GM1, GM2, GM3, GQ1b
106
What does ceramide synthesis require?
Serine, palmitoylCoA, FACoA, NADPH, FAD
107
What additions to ceramindes make distinct sphingolipids like sphingomyelin or globoside?
The addition of phosphoryl choline or sugar, acidic sugar, sulfate
108
What are sphingolipids degraded by?
Lysosomal enzymes (acid hydrolases-nucleases, proteases, glycosidases, lipases, phosphatases, sulfatases, phospholipases)
109
Where does the degradation of sphingolipids occur?
In lysosomes
110
What maintains the low pH in the lysosome?
A proton pump
111
What is the enzyme deficiency in Tay-Sachs disease?
Hexosaminidase A
112
What is the enzyme deficiency in Sandhoff disease?
Hexosaminidase A and B
113
What is the enzyme deficiency in Fabry's disease?
a-galactosidase
114
What is the enzyme deficiency in Krabbe's disease?
B-galactosidase
115
What is the enzyme deficiency in Gaucher's disease?
B-glucosidase
116
What is the enzyme deficiency in Niemann-Pick Disease?
Sphingomyelinase
117
What are the characteristics of Gaucher's disease?
B-glucocerebrosidase enzyme deficiency; Accumulate glucocerebroside; autosomal recessive
118
What are the characteristics of Tay-Sach's disease?
Hexosaminidase A is absent; Autosomal recessive; GM2 ganglioside accumulates; rapid and progressive neurodegeneration; blindness, cherry-red macula; muscular weakness; seizures; common in Ashkenazi Jews
119
What are the characteristics of Fabry disease?
Deficient in a-galactosidase A; X-linked recessive; accumulation of globosides; reddish-purple skin rash; kidney and heart failure; buring pain in lower extremities.
121
What is a potent regulator of cellular function and is produced by almost all cells?
Eicosanoids
122
What are some eicosanoids that are local hormones?
Prostaglandins, thromboxanes, leukotrienes
123
What are the functions of Eicosanoids?
Participate in the inflammatory response; regulate smooth muscle contraction; increase water and sodium excretion; involved in blood pressure regulation; constrictors and dilators of blood vessels; bronchoconstriction and bronchodilation
124
What is a fatty acid precursor to eicosanoids?
Arachidonic acid
125
What are eicosanoids made in respnose to?
Cytokine, hormone signals.
126
What are the three pathways for metabolism of arachidonic acid?
Cyclooxgenase, lipoxygenase, CYP450
127
What do prostaglandins work through?
Adenyl cyclase, cAMP, Protein Kinase A
128
What do PGF2, Thromboxane A2 and leukotrienes do in the cytosol?
Increase Ca2+
129
What is the lifespan of eicosanoids?
Seconds to minutes
130
What is the parent compound of prostaglandins?
prostanoic acid
131
What is the level of oxidation of PGA compared to PGF?
PGA is most oxidized; PGF is most reduced
132
What do PGI2, PGE2, and PGD2 increase?
Vasodilation and cAMP?
133
What do PGI2, PGE2, and PGD2 decrease?
Platelet aggregation; leukocyte aggregation; IL-1; IL-2; T-cell proliferation; lymphocyte migration.
134
What does PGF2a increase?
Vasoconstriction; bronchoconstriction; smooth muscle contraction
135
What is prostacyclin produced by?
Vascular endothelial cells
136
What does prostacyclin inhibit?
Platelet aggregation
137
What does prostacyclin cause?
Vasodilation
138
What is Thromboxane produced by?
Platelets
139
What does thromboxane do?
Stimulates platelet aggregation and causes vasoconstriction
140
What are prostaglandins inhibited by?
NSAIDs that block cyclooxygenase action
141
What does the lipoxygenase pathway form?
HETE's; Leukotrienes; and Lipoxins
142
What are leukotrienes?
Synthesized in leukocytes and contain 3 double bonds.
143
What does LTB4 increase?
Vascular permeability, T-cell proliferation, leukocyte aggregation, and IL-1 and IL-2.
144
What does LTC4 and LTD4 increase?
Vascular permeability and bronchoconstriction.
145
How many hydroxy groups do lipoxins contain?
3
146
What are examples of compounds produced from arachidonic acid by cytochrome P450?
Epoxide, Dihydroxide
147
In what areas are compounds produced from arachidonic acid by cytochrome P450 active?
Ocular, vascular, endocrine, and renal systems.
