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Plasma membrane Flashcards

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1
Q

3 main classes of membrane lipids

A
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2
Q

Are lipids polymers?

A

Ni

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3
Q

Lipids form membrane through ____ interactions

A

non-covalent

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4
Q

When a suspension of phospholipids is mechanically dispersed
in an aqueous solution,
the phospholipids aggregate into one of three structure
-> They are ___

A

1/ micelles
2/ Liposomes
3/ phospholipid bilayers

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5
Q

What is this?

A

Micelle

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6
Q

5 examples of Complex (hydrolyzable) lipids:

A
  1. triglycerides
  2. glycerophospholipids
  3. sphingolipids
  4. glycolipids (glycosphingolipids)
  5. plasmalogenes
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7
Q

Identify

A

Glycerophospholipids (general structure)

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8
Q

3 important examples of glycerophospholipids

A
  1. Phosphatidylcholine
  2. Phosphatidylserine
  3. Phosphotidulinositol 4-5-biphosphate
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9
Q

Identify this molecule

A

phosphatidylcholines

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10
Q

Products of this reaction

A
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11
Q

What happen to Phosphatidylserine when Ca2+ level elevates?

A

phosphatidylserine (PS) is externalized to the outer surface of the plasma membrane

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12
Q

Enzymes involving in Maintaining the membrane asymmetry of lipids?

A
  1. Flippases
  2. Scramblases
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13
Q

What is the role of Flippases?

A

move phospholipids (aminophospholipids) (e.g. phosphatidylserine) inwards, from the outer leaflet to the cytoplasmic leaflet of membranes.

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14
Q

Is flippase a transporter? If yes, is it required by ATP?

A

Yes, it is ATP-dependent

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15
Q

The role of Floppases?

A

Move choline-containing phospholipids to the outer leaflet

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16
Q

Do floppases require ATP?

A

YES!!!

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17
Q

What is the role of Scramblases?

A

equilibrate lipids across the bilayer

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18
Q

Do scramblases require ATP?

A

NO

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19
Q

Are all scramblases activated by calcium?

A

Some of them are activated by calcium.

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20
Q

When platelets are activated, what happen to the intracellular Ca2+ concentration?

A

It increases

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21
Q

When platelets are activated, the intracellular Ca2+ concentration increases.
-> This local Ca2+ increase inactivate (1)____ and activate (2)____.

A

1/ flippases
2/ scramblases

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22
Q

Name the 2 main enzymes involve in Breaking up phospholipid membranes

A
  1. (Pancreatic) phospholipase A2
  2. phospholipase C
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23
Q

What is the reaction catalyzed by (Pancreatic) phospholipase A2?

A
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24
Q

Structure of phosphatidylinositol bisphosphate (PIP2), showing sites of ____

A

cleavage

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25
Structure of phosphatidylinositol bisphosphate (PIP2), showing sites of cleavage by ___
different phospholipases
26
Structure of phosphatidylinositol bisphosphate (PIP2), showing sites of cleavage -> to produce ___ and ____
active mediators and summary diagram of the inflammatory mediators derived from phospholipids
27
What is the inhibitor of Phospholipase A2 activation?
Glucocorticoids
28
What is the role of TXA2
Thrombotic Vasoconstrictor
29
What is the inhibitor of Cyclo-oxygenase?
NSAIDs Glucocorticoids inhibit induction
30
What is the inhibitor of Phospholipase A2 activation?
Glucocorticoids
31
What is the inhibitor(s) of the process of making TXA2 from Cyclic endoperoxides?
TXA2 synthase inhibitors
32
What is the inhibitor of TXA2?
TXA2 anatagonists
33
What is the inhibitor of this process?
Leukotriene receptor for antagonists (e.g, zafirukast, montelukast)
34
What is the inhibitor(s) of these molecules?
PG antagonists
35
What is the role of TXA2
Thrombotic Vasoconstrictor
36
What is the role of PGI2
Vasodilator Hyperalgesic Stops Platelet aggregation
37
How does the hydrolysis of phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) occur?
38
The hydrolysis of PI(4,5)P2 by PLC -> What is the role of diacylglycerol after this?
Activates protein kinase C
39
The hydrolysis of PI(4,5)P2 by PLC -> What is the role of IP3 after this?
Releases Ca2+ from the endoplasmic reticulum
40
How does The phosphorylation of PI(4,5)P2 occur?
insulin, growth factor or cytokines bind to adaptor -> PI3K activates -> phosphorylation of phosphatidylinositol 4,5-bisphosphate occur
41
The structure of Sphingolipids
The sphingolipids contain sphingosine, a longchain aliphatic amino alcohol, but no glycerol.
42
3 important types of Sphingolipids
1. Sphingomyelin (phosphoric acid and choline.) 2. Neutral glycolipids (glucosylcerebroside) 3. Ganglioside GM2
43
Sphingolipids -> Name of X if this sphingolipid is Neutral glycolipids (glucosylcerebroside)
Glucose
44
Sphingolipids -> Neutral glycolipids (glucosylcerebroside) -> Name 3 other classes of sphingolipids
erebrosides, globosides, and gangliosides, which contain sugar components.
45
Sphingolipids -> Name of X if this sphingolipid is ganglioside GM2
Complex oligosaccharide
46
Enzyme deficiency of Hexosamindase (name of the disease)
Tay-Sachs disease (enzyme deficiency of ...)
47
Enzyme deficiency of alpha-galactosidase (name of the disease)
Fabry's disease (enzyme deficiency of ...)
48
Enzyme deficiency of Arylsulfatase A (name of the disease)
Metachromatic leukodystrophy (enzyme deficiency of ...)
49
Enzyme deficiency of Hexosamindase (name of the disease)
Tay-Sachs disease (enzyme deficiency of ...)
50
Enzyme deficiency of beta-galactosidase (name of the disease)
Krabbe's disease (enzyme deficiency of ...)
51
Enzyme deficiency of beta-glucosidase (name of the disease)
Gaucher's disease (enzyme deficiency of ...)
52
Enzyme deficiency of sphingomyelinase (name of the disease)
Niemann-Pick disease disease (enzyme deficiency of ...)
53
What does lipid raft contain?
It is enriched in sphingolipids, cholesterol
54
Which pathway is affected by Hypercholesterolemia?
LDL receptor pathway
55
The role of Cholesterol
changes membrane fluidity-
56
Cholesterol has a direct inhibitory effect on ___ in the ER
HMG-CoA reductase
57
What is Regulatory role of cholesterol, oxysterol?
58
Describe The fluid mosaic model of membrane structure
- The membrane consists of bimolecular lipid layer with proteins inserted init or bound to either surface - These proteins are integral protein, transmembrane protein and peripheral proteins
59
What are integral proteins?
Proteins that are firmly embedded in the lipid layers
60
What are transmembrane proteins?
Proteins that completely span the bilayer
61
What are peripheral proteins?
Proteins that are loosely bound to the outer and inner surface of the membrane
62
Identify this molecule
N-acetylneuraminic acid
63
What are proteoglycans?
core protein+ glucoseaminoglycans
64
What are glycoproteins?
protein+ oligosaccharides
65
Composition of the ABO antigens?
The ABO Antigens Are Glycosphingolipids & Glycoproteins present in most cells of the body and in certain secretions
66
For red blood cells, the membrane oligosaccharides that determine the antigenic natures of the ABO substances appear to be mostly present in (1)____, whereas in secretions the same oligosaccharides are present in (2)____
1. glycosphingolipids 2. glycoproteins
67
the blood group substances are biantennary -> Why?
they have two arms, formed at a branch point (not indicated) between the GlcNAc—R, and only one arm of the branch is shown.
68
This is a Diagrammatic representation of the structures of the H, A, and B blood group substances -> Explain
1. R represents a long complex oligosaccharide chain, joined either to ceramide where the substances are glycosphingolipids, or to the polypeptide backbone of a protein via a serine or threonine residue where the substances are glycoproteins. Note that the blood group substances are biantennary; ie, they have two arms, formed at a branch point (not indicated) between the GlcNAc—R, and only one arm of the branch is shown. Thus, the H, A, and B substances each contain two of their respective short oligosaccharide chains shown above. The AB substance contains one type A chain and one type B chain.
69
Glycophorin are rich in negatively charged ____ acids
sialic
70
Glycophorin molecules account for approximately 60% of ____
the RBC's negative surface charge
71
What is the role of Glycophorin
1. Modulating RBC-RBC interactions 2. RBC interactions with the vascular endothelium and other circulating blood cells.
72
What can decrease in erythrocyte glycophorin sialic acid content lead to?
increased erythrocyte aggregation
73
______ situated at the ends of the oligosaccharide chains of many (plasma) glycoproteins
The residues of sialic acid (n-acetylneuraminic acid, NANA, Neu5Ac )
74
Removal of the sialic acid residues by _____ (which enzyme?)
the enzyme sialidase (also called neuraminidase)
75
Why does removal of the sialic acid residues by the enzyme sialidase (also called neuraminidase) occur?
It is a one way in which the body marks “old” proteins for destruction and replacement.
76
The plasma membrane of hepatocytes contains _____
lectin molecules
77
The role of asialoglycoprotein receptors
Receptor- asialoglycoprotein interaction triggers endocytosis and destruction of the asialoglycoprotein.
78
Where can we find asialotransferrin?
It is found in CSF (cerebrospinal fluid), but not in normal serum or secretion fluids.
79
What can the detection of asialotransferrin from nose or ear suggest?
It suggests the possibility of CSF leakage, e.g. in patients with skull injuries.
80
What is the ratio of protein to lipid in human erythrocyte's membrane?
1.1
81
What is the ratio of protein to lipid in myelin's membrane?
0.23
82
What is the ratio of protein to lipid in mitochondrial inner membrane?
3.2
83
Does LDL - LDL-receptor depend on pH?
Yes
84
What happen On prolonged agonist activation of the G protein–coupled receptors (GPCR)?
selective GPCR kinases (GRKs) are recruited to the plasma membrane and phosphorylate the receptor ARR: Arrestin, Dyn: Dynamin GTPase→energy consuming process
85
Types of transported structures included in facilitated diffusion?
Transporter Channel
86
Types of transported structures included in primary active transport
1. ATPase 2. pump 3. ABC transporter
87
Types of transported structures included in secondary active transport
transporter
88
Hydrophobic molecules Small uncharged polar molecules Large uncharged polar molecules Ions => Ranking the permeabilities of these substances from high to low
1. Hydrophobic molecules 2. Small uncharged polar molecules 3. Large uncharged polar molecules 4. Ions
89
Are aquaporins permeable to protons?
NO!
90
Why are aquaporins impermeable to H+?
they prevent proton hopping by water dipole reorientation
91
What are the consequences of aquaporin channel mutation?
1/ Kidney – poliuria, polidipsia→diabetes insipidus 2/ Lens - cataract
92
Composition of Aquagliceroporins
1. Glycerol (adipocite, liver) 2. Urea (liver) 3. transport
93
Glucose transporters in Humans - GLUT1 -> Tissue(s) where expressed?
1. Erythrocytes 2. Blood-brain barrier 3. Placenta 4. Most tissues at a low level
94
Glucose transporters in Humans - GLUT1 -> What is the coding gene?
SLC2A1
95
Glucose transporters in Humans - GLUT1 -> Role/ characteristics?
1. Basal glucose uptake 2. Defective in De Vivo disease
96
Glucose transporters in Humans - GLUT2 -> Tissue(s) where expressed?
1. Liver 2. Pancreatic islets 3. Intestine 4. Kidney
97
Glucose transporters in Humans - GLUT2 -> Role/characteristics?
1. In liver and kidney 2. Removal of excess glucose from blood 3. In pancreas, regulation of insulin release
98
Glucose transporters in Humans - What is the coding gene of GLUT2?
SLC2A2
99
Glucose transporters in Humans - GLUT3 -> Tissue(s) where expressed?
1. Brain (neuron) 2. Testis (sperm)
100
Glucose transporters in Humans - GLUT3 -> Role/characteristics?
1. Basal glucose uptake 2. High turnover number
101
Glucose transporters in Humans -> What is the coding gene of GLUT3?
SLC2A3
102
Glucose transporters in Humans - GLUT4 -> Tissue(s) where expressed?
Muscle, fat, heart
103
Glucose transporters in Humans - GLUT4 -> Role/characteristics
Activity increased by insulin
104
Glucose transporters in Humans What is the coding gene of GLUT4
SLC2A4
105
Glucose transporters in Humans - GLUT5 -> Tissue(s) where expressed?
1. Intestine (primarily) 2. Testis 3. Kidney
106
Glucose transporters in Humans - GLUT5 -> Role/characteristics?
Primarily fructose transport
107
What is the role of solute-carrier gene (SLC)?
solute-carrier gene (SLC) superfamily encodes membrane-bound transporters
108
Glucose transporters in Humans -> What are the expressed tissue(s) of GLUT 9?
Liver, kidney, intestine, lung, placenta
109
Glucose transporters in Humans -> Role/characteristics of GLUT 9
Urate and glucose transporter in liver, kidney
110
Comparison of theme concentrations of Na+, K+, Ca2+ outside and inside a mammalian cell?
111
What are The four classes of ATP-powered transport proteins?
1/ P-class pumps 2/ V-class proton pumps 3/ F-class proton pumps 4/ ATP-binding cassette transporters
112
The four classes of ATP-powered transport proteins -> Where do P-class pumps present?
1. Plasma membrane of higher eukaryotes (Na+/K+ pump) 2. Apical plasma membrane of mammalian stomach (H+/K+ pump) 3. Plasma membrane of all eukaryotic cells (Ca2+ pump) 4. Sarcoplasmic reticulum membrane in muscle cells (Ca2+ pump)
113
The four classes of ATP-powered transport proteins -> Where do V-class protons pump present?
1/ Endosomal and lysosomal membranes in animal cells 2/ Synaptic vesicles
114
The four classes of ATP-powered transport proteins -> Where do F-class protons pump present?
Inner mitochondrial membrane
115
The four classes of ATP-powered transport proteins -> Which 7 molecules can you find on ATP -binding cassette transporters?
1/ ABCA1 2/ P-glycoprotein 3/ MRP1 4/ MRP2 5/ ABCG5/ABCG8 6/ CFTR
116
ATP -binding cassette transporters -> The role of ABCA1?
HDL metabolism, reverse cholesterol transport
117
ATP -binding cassette transporters -> The role of ABCB1 / P-glycoprotein / multidrug resistance protein 1 (MDR1)?
resistance to chemotherapy
118
ATP -binding cassette transporters -> The role of ABCC1 / MRP1?
multidrug resistance
119
ATP -binding cassette transporters -> The role of ABCC2 / MRP2?
conjugated bilirubin (Dubin-Johnson syndrome)
120
ATP -binding cassette transporters -> The role of ABCG5/ABCG8?
cholesterol (liver, intestine)

Biochem 2 (38 decks)

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