Lipids Flashcards
1
Q
Defined as biosynthesis of fatty acid
A
Lipogenesis
2
Q
Three types of lipogenic pathways based on cellular localization
A
Extramitochondrial
Microsomal
Mitochondrial
3
Q
Extramitochondrial lipogenesis pathway occurs in
A
Cytosol
4
Q
Microsomal lipogenesis pathway occurs in
A
Smooth endoplasmic reticulum
5
Q
Mitochondrial lipogenesis pathway occurs in
A
Mitochondrion
6
Q
General principle of lipogenesis is
A
Add 2 carbon atoms per cycle
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
8
Q
In the extramitochondrial lipogenesis pathway, Acetyl CoA is converted to
*rate-limiting step
A
malonyl CoA
9
Q
Is the rate-limiting step or committed enzyme in extramitochondrial lipogenesis
A
Acetyl CoA Carboxylase
10
Q
Prosthetic group of Acetyl CoA
A
Biotin
11
Q
Acetyl CoA carboxylase for conversion of acetyl coa to malonyl coa is inhibited by
A
palmitic acid
12
Q
A protein found in raw egg white, inhibits the committed step by binding and removing biotin
A
Avidin to acetyl carboxylase
13
Q
Energy source per gram of lipid
A
9 calories
14
Q
Adipose ->
A
Fatty acids -> CO2 + H2O + ATP
15
Q
Major components of cell membranes
A
Phosphoglycerides
Sphingolipids
Cholesterol
16
Q
Lipid classes
A
Fatty acid derivatives Triacylglycerol (TAG) Phospholipids Sphingolipids Wax esters Isoprenoids (terpenes, steroids) Lipoproteins
17
Q
2-4 carbon atom Fatty acids
A
Short
18
Q
6-10 carbon atom fatty acid
A
Medium
19
Q
12-26 carbon atom or more fatty acid
A
Long
20
Q
Have only single bonds in hydrocarbon chain
A
Saturated fatty acid
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
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
23
Q
The greater the degree of unsaturation,
A
the lower the melting point
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
25
22 Carbon Double-Bonds with Methyl, Oil-soluble, Omega End and Carboxyl, Water-Soluble Delta End
```
Docasahexaenoic Acid (DHA)
Omega 3
```
26
18 Carbon Double-Bonds with Methyl, Oil-soluble Omega end and Carboxyl, Water-Soluble Delta end
Gamma-linolenic Acid (GLA)
| Omega 6
27
20 Carbon Double-bonds with Methyl, Oil-Soluble Omega End and Carboxyl, Water-Soluble Delta End
Dihomo-gamma-linolenic Acid (DGLA)
| Omega 6
28
Polyunsaturated >2 double bonds
Not synthesized by body
Decrease risk of Cardiovascular Disease
Polyenoic fatty acids
Essential fatty acids
Omega 3
Omega 6
29
C18 having two double bonds
Linoleic acid
Lady linoleic linolenic
30
C18 having three
Precursor of EPA (eicosapentaenoic acid) and DHA (docosahexanoic acid)
Linolenic acid
31
C20 having four double bonds
Arachidonic acid
32
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
TAG
33
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
TAG
34
Molecules are classified according to which alcohol becomes esterified to the phosphate group
Phosphoglyceride
35
```
Phosphatidylcholine (PC or Lecithin)
Phosphatidylethanolamine
Phosphatidylserine
Diphosphatidylglycerol
Phosphatidylinositol
```
Phosphoglyceride
36
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
Lecithin
| Phosphatidylcholine
37
Serologic test for syphilis
Utilizes a diphosphatidylglycerol as the antigen
Venereal Disease Research Laboratory
Cardiolipin
38
With repeating 5-carbon units (isoprene)
Terpenes
Steroids
Isoprenoids
39
Mixed terpenoids
```
Vitamin E (alpha tocopherol)
Ubiquinone
Vitamin K
```
40
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
Steroids
41
Ovarian steroid
estrogen
42
18 Carbon atoms
The A ring of the steroid nucleus of estrogen is aromatic
Estrogen
43
Has OH groups attached to carbons 3 and 17
Estradiol
44
Produced in the adrenal cortex and the testes
19 Carbon atoms
Testosterone
Dehydroepiandrosterone
Androgens
45
One of the more potent androgen
Testosterone
46
Unlike testosterone is a 17-ketosteroid
Dehydroepiandrosterone (DHA)
47
Synthesized in the corpus luteum
| Has 21 carbons
Progesterone
48
A potent glucocorticoid with weak mineralocorticoid activity
Cortisol
49
Is a potent mineralocorticoid but a weak glucocorticoid
Aldosterone
50
This assay detects all 21-carbon steroids with a 17-OH group, such as cortisol
Urinary 17-hydroxycorticosteroid
51
Lipids must bind to proteins to make them water-soluble for transport in the blood
Lipoproteins
52
Are the least dense lipoproteins
After a fatty meal, the blood appears milky due to the high concentration of chylomicrons
Chlyomicrons
53
An anticoagulant also helps to clear chylomicrons from the blood, perhaps by stimulating lipoprotein lipase
Heparin
54
The inherited absence of lipoprotein lipase causes
Hyperchlyomicronemia
| Frederickson’s type I hyperlipoproteinemia
55
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
Very low-density lipoproteins (VLDL)
56
Is synthesized in the liver
This fraction is markedly elevated in type IV hyperlipoproteinemia
VLDL
57
Contain mainly cholesterol in contrast to the content of chylomicrons and VLDL
LDL
58
They migrate together with B-globulins
They are termed B-lipoproteins
LDL
59
The fraction is markedly elevated in Type II Hyperlipoproteinemia and is associated with a high incidence of atherosclerosis
LDL
60
Contain mainly protein and phospholipid
They contain significant amounts of cholesterol but have little triglyceride
High density lipoproteins HDL
61
The high protein, low triglyceride content makes them very dense
They are termed alpha-Lipoproteins
High density lipoprotein HDL
62
3 main classes of lipids are found in biological membranes:
Phospholipid
Glycolipid
Cholesterol
63
Lipid bilayer is
amphipathic
64
“Water-loving” polar head group
Hydrophilic
65
“Water-hating” non-polar tails
Hydrophobic
66
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
```
Tangiers disease
| Familial Alpha Lipoprotein Deficiency
67
Tangiers disease results from a mutation of a transmembrane protein that transports phospholipid & cholesterol out of the liver to generate HDL
ABCA1
68
Functions of lipid
As energy source 9kcal/gram
Protein sparer
Facilitates absorption of fat soluble vitamins
69
The only absolute essential fatty acid (EFA)
Precursor of arachidonic acid
Linoleic acid
70
FA that reduces risk of heart disease
Omega 3
71
FA that potentially significantly improves autism
Docosahexanoic acid
| Omega 3
72
Extramitochondrial lipogenesis
Sources of NADPH
HMP shunt
| Malic enzyme reaction (Malate -> Pyruvate)
73
Rate limiting step of extramitochondrial lipogenesis
by enzyme
Conversion of acetyl coA to malonyl coa
acetyl coa carboxylase
74
18 C
soaps, shampoos, detergents, shaving creams
Stearic acid
75
16 C
Palmitic acid
76
Body can synthesize needed fat except
Linoleic
| Alpha linolenic
77
Alpha linolenic acid
Omega 3 FA
78
Linoleic acid
Omega 6 FA
79
Omega 3 fatty acids
```
Alpha linolenic acid (ALA)
Eicosapentanoic acid (EPA)
Docohexanenoic acid (DHA)
```
80
Nerve problem treatment
ALA
81
Omega 6 Fatty acid
Linoleic acid
82
Omega 3
Alpha Linolenic Acid (ALA)
then
```
Eicosapentaenoic acid (EPA)
Docosahexaenoic acid (DHA)
```
83
Intestinal mucosal cells secrete nascent TG-rich
chylomicrons
84
Liver secretes nascent TG-rich
VLDL
85
Neutral lipid core (triacylglycerol + cholesterol ester) surrounded by a shell of apolipoproteins, phospholipids, nonesterified cholesterol
Soluble in aqueous solution
Lipoprotein
86
Lipoprotein with lowest density
Largest in size
Most lipid
Smallest percentage of protein
Chylomicron
87
Chylomicron inherent apolipoprotein
ApoB-48
88
Nascent VLDL (liver) inherent apolipoprotein
Apo-B100
89
Transferred from HDL to nascent CM and VLDL
ApoCII
| ApoE
90
Activated by apoCII and degrades triacylglycerol in chylomicrons and VLDL
Found in capillaries of tissue adipose, cardiac and skeletal muscle
Lipoprotein lipase
91
Lipoprotein lipase degrades (hydrolyzes) TAG of chylomicrons and VLDL into
Free fatty acid
Glycerol
Monoacylglycerol
and be sent back to Liver
92
Most electrophoretic mobile lipoprotein
Chylomicron
93
Least electrophoretically mobile lipoprotein
HDL
94
Deficiency of lipoprotein lipase or apo-CII
Dramatic accumulation of triacylglycerol rich lipoproteins in plasma
Type I Hyperlipidemia
| Familial hyperchylomicronemia
95
C apolipoproteins after activation of lipoprotein lipase are returned to
HDL
96
The cholesterol released from chylomicron regulates the
Rate of de novo synthesis of cholesterol
Inc cholesterol from chylomicron decreases HMG Coa reductase
allosterically inhibits the enzyme
97
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
VLDL
98
Once degraded, apo C-II and apo E go back to HDL and in exchange,
cholesteryl ester from HDL are transferred to VLDL with concomittant TAG and phospholipid transfer from VLDL to HDL
99
Transfer of cholesteryl esters from HDL to VLDL in exchange for triacylglycerol or phospholipid is accomplished by
cholesteryl ester transfer proteins
100
In the plasma, after exchange of cholesteryl ester VLDL is transformed into
LDL
101
Intermediate sized particle observed during transition from VLDL to LDL
Intermediate density lipoprotein
102
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
LDL
103
Deficiency of functional LDL receptors on cell surfaces causing significant elevation of LDL and cholesterol
BUT NORMAL TAG
Type II hyperlipidemia
Familial hyperbetalipoproteinemia
accelerates atherosclerosis
104
Degrades TAG containing SHORT FATTY ACIDS
Secreted by stomach on the stomach
Gastric lipase
105
Degrades TAG (removes fatty acid from carbon 1, 3 leaving monoacylglycerol)
Requires pancreatic colipase for stabilization
Secreted by pancreas and sent to intestines
Pancreatic lipase
106
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
Lipoprotein lipase
107
Degradation of stored triacylglycerol
Activated by cAMP dependent protein kinase
Secreted by adipocytes in the adipocyte cytosol
Hormone sensitive lipase
108
Removes fatty acid from lipids taken into cells during phagocytosis
Acid pH optimum
Secreted by most tissues acts on lysosomes
Acid lipase
109
Functions of HDL
synthesized in liver and released by exocytosis
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
Decreased concentration of plasma cholesteryl ester due to deficiency in
PCAT
| phosphatidylcholine production
111
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
apolipoprotein a
