Lipids/Cell Membrane Flashcards
(157 cards)
1
Q
Property of lipids
A
Heterogeneous group of compounds, share: 1. Insolubility in water based solutions. 2. Solubility in organic/non-polar solvent.s
2
Q
Normal saturated fatty acids are generally more soluble in __?
A
Chloroform
3
Q
SA FA are generally less soluble in __ ?
A
Acetonitrile
4
Q
5 Biological Functions of Lipids?
A
Storage of Energy Membrane Structure Signalling Molecules Cofactors for enzymes Antioxidants
5
Q
Branch 1 Classification of Lipid
A
Complex and Biologically Active Lipids
6
Q
Difference between Complex and Biologically Active Lipids
A
Complex = FA Biologically active = NO FA
7
Q
Branches of complex lipids (FA)?
A
Storage and Structural Lipids
8
Q
Difference between storage and structural lipids?
A
Storage = non-polar Structural = polar
9
Q
examples of storage (non-polar) lipids
A
Triglycerides Waxes
10
Q
examples of structural (polar) lipids
A
Phospholipids Sphingolipids
11
Q
Examples of biologically active lipids (No FA)
A
Prostaglandins Steroids
12
Q
Define fatty acid
A
Amphipathic molecules with hydrocarbon chains containing 3 to 35 carbons plus carboxylic group.
13
Q
pKa of COOH groups?
A
<5 … therefore will be fully ionized after this time.
14
Q
Almost all natural FA have ____
A
an even # of carbons
15
Q
FA can be ___
A
saturated or unsaturated
16
Q
What are FA physical properties based on?
A
1) Length of hydrocarbon chain 2) Degree of saturation
17
Q
All naturally occurring double bonds have __
A
CIS configuration
18
Q
Most common FA length?
A
C14 to C18
19
Q
What is interesting about the 4 carbon FA, or butanoic acid?
A
-infinitely water soluble -solubility decreases w/ increased hydrocarbon chain length.
20
Q
Solubility of Lauric acid? (12 carbon FA?)
A
partially soluble to the extent of 0.06g per gram of water
21
Q
Fatty acids with C10 or greater form ___ at room temp
A
Waxy solids
22
Q
Fatty acids with C9 or lower saturates or unsaturated HC chains form ___ at room temperature?
A
Oily solids
23
Q
What does the prefix “alpha” indicate?
A
Normal or unbranched structure. i.e alpha-linolenic acid.
24
Q
Double bonds in FA chains produce what?
A
kinks and bends
25
Due to kinks and bends in unsaturated FA ... this causes what?
1) Unsaturated FA are LESS packed VS saturated 2) LESS ordered packing = WEAKER intermolecular interactions (vanderwall forces) 3) LOWER melting points for unsaturated fatty acids.
26
Which fatty acids can humans not synthesize? Why do we need them?
LinoLEIC acid, Omega 6. LinoLENIC acid, Omega 3. Need them to synthesize other needed FA, such as AA, DHA, EPA and n-3 and n-6 eicosanoids.
27
Importance of omega 3?
-inhibit formation of thromboxane A2 (eicosanoids) -\> associated with platelet aggregation + clot formation.
28
Omega 3 FA are associated with decrease risk of what disease?
Coronary diseases
29
3 major typed of omega 3 fatty acids?
-alpha linolenic cid (ALA) -EPA -DHA
30
What are the effective PUFA's?
EPA DHA
31
Characteristics of Trans Fatty Acids?
-partially hydrogenated - trans double bond -\> adapt an extended conformation -more regularly packed -higher melting points
32
Formation of trans fatty acids?
partial hydrogenation on unsaturated fatty acids + cis-double bond Isomerization to trans double bonds
33
Example of hydrogenation?
Peanut butter from peanut oil
34
Why is high sat fat (animals) and trans fat (animals/plant) bad for health?
-SFA increase blood cholesterol by providing proper packing domains for cholesterol. -TF do the same, due to increase rigidity around the double bonds
35
Correlation between high cholesterol and higher incidence of heart disease, why?
Reduced membrane Fluidity Reduced membrane Flexibility Reduced membrane protein Functions
36
What is Anandamide?
Signalling molecule, found in brain + chocolate and turns on same receptor as marijuana. May explain cravings for some individuals for chocolate.
37
How are triglycerides formed?
-condensation reaction, where H is lost from glycerol, OH is lost from fatty acid
38
Acylglycerides are linked by __ ?
ester linkages
39
What increases solubility of a FA? Why?
shorter hydrocarbon chain increases solubility, more easily interacts with water
40
What increases melting point of a FA? Why?
Increased degree pf saturation. Allows for more ordered packing + more inter molecular vanderwaals forces .. . therefore melting point increases.
41
fatty acids found in complex lipids are responsible for what?
Formation of micelles in aqueous solutions.
42
The glycerol moiety of a TG has a centre of ?? at the second carbon atom?
Asymmetry
43
Triglycerides can be assembled with what?
Acyl transferase
44
Triglycerides can be disassembled with what?
Lipase
45
Where are TGs store in animals? Plants?
Fat cells, and seeds
46
What is the most abundant form of metabolic storage lipids?
Tri-acylglycerols
47
Most defining characteristic of triglycerides?
Both plant and animal format are insoluble.
48
Animal triglycerides are \_\_
solid at room temp
49
Plant triglycerides are\_\_\_\_
liquids (oil) at room temp.
50
What important aspect does fat and oil differ?
Degree of unsaturation
51
How can a TG be simple?
if all fatty acids are of the same length
52
How can a TG be complex/mixed?
If all 3 FA are of different lengths and saturation
53
TG are considered what compared to sugar?
A light source of energy.
54
Advantage of fats over polysaccharides
-Acylglycerides carry more energy per carbon because they are more reduced. -FA carry less water along because they are non polar.
55
Glucose + glycogen are
short term energy needs and allow for quick delivery
56
Acylglycerides are for
long term (months) energy needs, good storage and long delivery
57
Where are TGs digested?
Small intestine by pancreatic lipase
58
Monoacylglycerides are absorbed where?
Into intestinal cells, and are converted in TG and packaged into lipoproteins (chylomicrons)
59
Treatment of TG with what leads to the hydrolysis of ester bond linkage?
Strong Acids or bases
60
Formation of soaps?
Hydrolysis w/strong acids/bases leads to fatty acid salts and glycerol (amphipathic) molecules that can be used.
61
How are waxes formed?
Condensation reaction between long FA and alcohol carbon chains
62
Defining of property of waxes?
Do NOT contain glycerol
63
What do waxes act as?
-metabolic fule -water impermeable coating
64
Melting temp of waxes?
-60-100 degrees C HIGHER THAN TG
65
Waxes are broken down with what?
Strong acids and bases
66
What are the two structural lipids?
Phospholipid Sphingolipids
67
2 other names for phospholipids?
Phosopho-acylglycerols Glycerophopholipids
68
Which carbon is the head phosphate group / located on?
C3
69
When are phosphatidic acids - charged?
ph 7
70
What is a phophatidic acid?
basic unit of phospholipid made up of 1,2-diacylglyecerol and linked to phosphoric acid
71
Which carbon are fatty acids linked to?
C1 and c2
72
where is phosphoric acid linked to?
3rd hydroxyl glycerol
73
what kind of bond attaches phosphoric acid and glycerol?
Phospho-ester bond
74
Fatty acids attached the C1 of carbon are usually?
Saturated
75
Fatty acids attached to C2 of carbon are often?
Unsaturated
76
Alcohol based compounds linked to phophatidic acids are known as?
head groups
77
Glycerol 3-phosphate is \_\_\_
the CHIRAL backbone of phospholipids
78
When can the C3 phosphate be considered phosphatidic acid? What will the net charge be?
when the head group = H -1
79
Which Head groups create a neutral phospholipid?
Ethanolamine Choline
80
Which her groups createa negative phospholipid?
-Serine -Glycerol -myo-Inositiol 4,5-bisphosphate -Phosphatidyl-glycerol
81
Diacylglycerol + Phosphoric Acid =
Glyecrophospholipid
82
what determines surface properties of glycerophospholipids?
Properties of head groups!
83
Different organisms have different ____ lipid head group compositions
Membrane
84
Different tissues have different ____ lipid head group compositions
Membrane
85
Major component of most eukaryotic cell membranes?
Phosphatidylcholine Net Charge of zero Head group = choline
86
Why can't many prokaryotes synthesize phosphatidylcholine?
because it does not appear within their membranes
87
How are glycerophospholipids similar? different
Similar: all are amphiphatic with charged head groups BUT they will differ in net charge!
88
Structure of Sphingosine
Sphingosine (C3 + backbone) attached to a fatty acid (C2) and a head group (C1)
89
Phophocholine at attached where on sphingolipid, what is the bond called?
C1 Phosphoester bond
90
Sphingomyelin, has what C1 group?
Phosphocholine
91
neutral Glycolipids -\> glucosylcerebroside has what C1 group?
Glucose
92
Glucose is attached where on sphingolipid, what s the bond called?
Glycosidic bond
93
Lactosylceramid (globoside), has what c1 group?
Di-tri or tetrasaccharide
94
Ganglioside GM2 has what c1 group?
Complex oligosaccharide
95
What is the backbone of sphingolipids?
Long-chain amino alcohol -\> sphingosine
96
What kind of linkage joins FA to sphingosine on C2?
Amide linkage
97
Joining of one FA via amide linkage on C2 to sphingosine gives what? What is it structurally similar to?
Ceramide, structurally similar to a diacylglycerol
98
Addition of phosphoric choline group =
sphingosine -\> sphingomyelin
99
Addition of sugar group =
sphingosine -\> cerebroside
100
Addition of combination of sugars (oligosaccharides)=
sphingosine -\> ganglioside
101
cerebrosides and gangliosides are largely doubt where? What is the downside of this?
-outer face of plasma membranes, consequently detectable by the immune system.
102
Glycosphingolipids blood groups are determined by what?
-type of sugars located on the head groups
103
Structure of sugar on head group of glycosphingolipids are determined by what?
expression of specific glyocosyltransferases
104
individuals with inactive glycosyltransferase will have the :
O antigen
105
Individuals with glycosyltransferase that transfers N-acetylgalactosamine will have:
A blood group
106
Individuals with the glycosyltransferase that transfers a galactose group will have the:
B blood group
107
what do all blood groups have in common?
Galactose Fucose N-acetly-glucosamine Red Blood cell
108
What do biologically active lipids not contain? How can they be generated?
Fatty acids or glycerol back bone. Can become generated by fatty acids
109
What is the major physiologic role of BAL?
-recruiting the activities of proteins and receptors
110
Importance of steroids?
-metabolically for digestions, bile salts. -hormones (sex hormones)
111
What are the major classes of BAL?
Prostaglandins Sterols
112
How are prostaglandins generated?
Modification of fatty acids
113
how are sterols generated?
From two carbon acids (acetate) and from modification of other sterols.
114
How do cells turnover their lipids in lysosomes?
By cleavage of ester linkages by 4 phospholipase
115
Name the 4 phospholipase
A1 A2 C D
116
Phospholipase A1 cleaves what bond?
C1 ester linked FA
117
Phospholipase A2 cleaves what bond?
C2 ester linked FA
118
Phospholipase C cleaves what bond?
C3 phophoester linked phosphoric acid
119
Phospholipase D cleaves what bond?
Phosphoeter linked X or head groups
120
What are the two classes of Phospholipases?
-Phospholipid-specific lipase -Broad substrate phosphoplipases
121
Which specific phospholipase hydrolysis is important in Protein Kinase C pathway ?
Phosphatidylinosital 4,5-bisphosphate
122
describe the sequence that occurs with protein kinase C pathway
All driven by kinases .. Signal will come into receptor, binds to receptor and will activate lipase. this lipase will then continue to cleave head group + generate lipids.
123
PMA is a dietster of what and what does it promote?
Phorbol, a tumor promotor by activating the signal transduction enzyme of protein kinase C
124
What are paracrine lipid hormones?
hormones which are present in small amount and play vital roles as singling molecules between nearby cells.
125
Enzymatic oxidation of arachidonic acid yields:
-Prostaglandins -Thromboxanes -Leukotrienes (PLT)
126
What does NSAID stand for, what do they do?
Non steroidal Anti Inflammatory drugs (aspirin, ibuprofen) Block cycloxygenase and prevents production of PLT
127
What do prostaglandins do?
Involved in inflammation + fever smooth muscle contraction in uterus
128
What do thromboxanes do?
Vasoconstrictor and facilitates platelet aggregation (heart disease link?)
129
What do Leukotrienes do?
Smooth muscle contraction in the lungs
130
What are the building blocks of cholesterol?
-Vitamins (KEA) -Cartenoids -Plant Hormones (Abscisic, Gibborelic acid) -Rubber -Phytol Chain of Chlorophyll -Quinone Electron Carriers (Ubiquinone, Plastiquinone) -Isoprene
131
What does Cholesterol give rise to?
Steroid Hormones Bile Acids Vitamin D
132
What steroid hormones does cholesterol give rise to?
-Testosterone -estradiol -Cortisol -Aldosterone (TECA)
133
Properties of sterol?
-Steroid nucleus: 4 fused rings -Hydroxyl group (polar head) on the A-ring. -Various non-polar side chains. -Steroid nucleus is almost planar.
134
Describe Cholesterol
-steroid w/ hydrophobic tail in two parts: -rigid planar rings and flexible/branched hydrocarbon chain.
135
What is the hydrophilic part of cholesterol?
Hydroxyl (head) group.
136
Since cholesterol is an amphipathic molecule, what is its function\>=?
Often a structural lipid within the cell membrane.
137
What does the structure of cholesterol prevent?
Promotes tight packing of UPPER ends of the fatty acids hydrocarbon tails, therefore INCREASING the melting point of the lipid bilayer.
138
Why is cholesterol known as the fluidity buffer?
because is will increase the melting point of the lipid bilayer due to its dense packing up upper ends of FA hydrocarbon tails
139
The fluidity buffer does what?
decreases the sharpness of the Gel to liquid crystalline transition.
140
The rigid structure of cholesterol favours what?
-interaction w/ saturated or tran fat unsaturated lipid ... these fats enhance cholesterol accumulation within the membrane!!
141
Describe Lipid Micelles
-small spherical structures -water is EXCLUDED from interior -Free FA and some detergents assume this conformation because the size of the head to tail ratio is MORE than 1
142
Describe lipid bilayer
-Sheet like structure with two monolayer -water is EXCLUDED from interior -Phosphoacylglyceride + Sphingolipids favour this lipid aggregates because the size of the head to tail ration is EQUAL to 1
143
describe Liposomes
-Hollow sphere of lipid bilayer folded back onto itself -Aggregates ENCLOSE water, thus act as barriers between two environments.
144
How does cholesterol maintain integrity of membrane as temp increases?
As temp increase, FA moves too much, rigidity of cholesterol helps keep them in place and maintain integrity.
145
How does cholesterol maintain integrity of membrane as temp decreases?
As temp decreases, FA will have tendency to crystallize. Cholesterol blocks the intermolecular interaction (vanderwall forces) between adjacent FA and maintains integrity.
146
If we decrease membrane temp, what do we add?
Increase amount of Unsaturated fat. unsaturated fat has a lower melting point, therefore counteracting the crystallization effect within the membrane.
147
If we increase membrane temp, what do we add?
increase amount of saturated fat. Saturated fat has a higher melting point, therefore counteracting the liquid effect.
148
What can we find within the cell membrane?
Glycolipids Peripheral Proteins Integral Proteins Glycoproteins Cholesterol Phospholipids
149
Cell membrane is permeable to: (WHN)
hydrophobic molecules neutral gases water
150
Cell membrane is impermeable to: (PLC)
Proteins Large Molecules Charged Ions
151
Lipids can diffuse through the cell membrane ..
LATERALLY only
152
Describe Uncatalyzed membrane diffusion
-Lipids only FAST! (~1um/s)
153
Describe Uncatalyzed transbilayer (Flip Flop)
-Very Slow No Lipids (t1/2 in days0
154
List the 3 kinds of catalyzed trans membrane translocations
Flippase Floppies Scramblase
155
What is required for Flippase? Where does the phospholipid flip?
-Ptype ATPase Moves from outside to INSIDE
156
What is required for Floppies? Where does the phospholipid flip?
-ABC transporter moves from inside to OUTSIDE
157
What is required for Scramblase? Where does the phospholipid flip?
Will flip in both directions to establish equilibrium.
