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IMS > Membranes and lipids / signalling > Flashcards

Membranes and lipids / signalling Flashcards

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1
Q

Hydrophillic heads of the bilayer lay where?

A

Outside of the bilayer

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2
Q

The tails of the bilayer lay where?

A

Inside the bilayer spontaneously forming a bilayer

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3
Q

Glycerophospholipids form a major class of membrane lipid derived from what?

A

Glycerol-3-phosphate

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4
Q

How many fatty acid tails does a glycerophospholipid have?

A

2

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5
Q

glyderophospholipid plus water =

A

phosphotidic acid

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6
Q

What does translocase do?

A

Moves the phospholipids across the membrane

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7
Q

What does scramblase do?

A

scramblase enzymes that randomise the normal membrane distribution of headgroups and undo the work of the translocases. (usually switched off) but can be turned on in platelet activation or sperm fertilising an egg.

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8
Q

What is the role of caveolin?

A

Int he formation of caveole and invaginate, which is one way that certain viruses can be internalized into cells.

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9
Q

What are the two most common R groups of glycerophospholipids?

A

Stearate and Palmitate

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10
Q

Phosphatidylserine plays an important role in which bodily process?

A

When platelets are activated, this leads to exposure of Phosphatidylserine and allows interaction of clotting factors.

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11
Q

Phosphatidylserine signal can trigger what?

A

Apoptosis “eat me”

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12
Q

What introduces double bonds into FA?

A

Desaturase

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13
Q

What are sphingolipids?

A

Sphingosine plus a palmitatae residue and choline head

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14
Q

Cholesterol causes what in the membrane?

A

less fluidity

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15
Q

Examples of peripheral membrane proteins?

A

Spectrin,actin and ankyrin

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16
Q

Apolipoprotein (E4) is associated with?

A

Increased prevalence in alzheimers

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17
Q

Amyloid beta peptide is the precursor to what?

A

Amyloid beta peptide

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18
Q

Where does O-linked glycosylation attach?

A

To serine or threonine residues

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19
Q

N linked glycosylation attaches to what and can never e attached to what?

A

Asparagine X thr or ser …. X can never be proline

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20
Q

Examples of substances diffused passively across membrane include?

A

02 C02 urea

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21
Q

How does passive mediated transport occur and what does it transport?

A

Down a conc gradient, glucose for example using integral membrane proteins

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22
Q

How many subunits are in an aquaporin and where are they located?

A

Erythrocytes and kidneys

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23
Q

An example of a symport transport system is?

A

Na+ and Glucose system

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24
Q

An example of an antiport system is what?

A

The Na+ and Ca2+ system

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25
What do apolipoproteins do?
Determine the start and end point for cholesterol in the blood
26
What is a CHYLOMICRON and found where?
Found in intestine and transport the triglycerides and cholesterol into the blood
27
Where do chylomicrons go when they have shrunk?
They go back to the liver
28
What are VLDLs
Made by liver and transport lipids to target tissues then acted upon by lipoprotein lipase to release FA
29
Where do VLDL remnants remaina nd what do they end up as?
In the blood ending up as LDLs
30
What happens to LDL in the blood?
Taken up by LDL receptors, digested and then release the cholesterol inside
31
Apo A =
HDL cholesterol to liver (good cholesterol)
32
Apo B=
LDL Uptake
33
Apo C
activated lipopretein lipase (transfer between lipoproteins)
34
Apo E
Stabilises VDL for uptake an a ligand for the Apo B/E (LDL) receptor
35
Why is HDL good cholesterol?
the apo A-I and AII confer resistance to oxidation HDL scavenges cholesterol .
36
What are the bad lipoproteins on the LDL?
Apo B100 and Apo e
37
High intracellular cholesterol suppresses what?
Uptake of cholesterol (LDL receptor) so it remains in the blood = bad
38
What is lipoprotein A and what does it do?
Badddddd not known exactly why but linked to an increase in cardiovascular disease.
39
What is an important intermediate in the production of cholesterol?
Mevalonate
40
What is prenylation?
Attaching a lipid tail onto an intracellular signalling molecule.
41
Ras prenylates with?
Farnesylpyro
42
Rho prenylates with?
Geranylgeranylpyro
43
What are the three ways of extracellular signalling?
Signalling by secreted molecules, Juxtacrine and via gap junctions
44
Examples of first messengers?
Growth factors, neurotransmitters, and hormones synthesises by signalling molecules
45
Receptors for hydrophillic molecules are where?
On the membrane (catecholamines)
46
Receptors for lipid based molecules are where?
Inside the molecule (steroids/thyroid)
47
4 types of receptor, what are they?
Ligand gated ion channels, GPCR, Kinase linked and nuclear receptors
48
How many domains does a GPCR have?
7 membrane spanning domains, alternating loops of alpha helices.
49
How many subunits surround the pore of a ligand gated ion channel?
4-5
50
What is on the extra an cytosolic domains of a GPCR?
NH2 outside COOH inside
51
Angiotensin I and II are examples of what?
molecules that use GPCR's
52
Angiotensin one causes what?
Vasoconstriction increased na+ absorption and aldosterone secretion
53
Angiotensin 2 causes what?
Antihypertensive, opposite to angiotensin 1
54
How many transmembrane complexes are in a kinase linked receptor?
1
55
What is the composition of the transmembrane domain of a kinase linked receptor?
Single helix, large extracellular and intracellular catalytic domain
56
catalytic kinase receptor usually involves what ?
an enzyme binding of insulin for example
57
non catalytic kinase receptor involves what?
Tyrosine and cytokines intracellularly, involves dimerisation following ligand binding
58
How does dimerisation act on cells?
Indirectly influencing gene transcription
59
Examples of molecules that use ligand gated ion channels?
nAchR Gaba 5-HT3R
60
How do nuclear receptors exert their effects?
Forming hormone receptor complexes, bind to regions of DNA and affect the DNA gene transcription.
61
What is the natural "cannabis"?
Anandaminde (type of lipid)
62
Endorphins, substance P and neurokinkins are examples of?
peptides
63
Histamine, adrenaline and dopamine examples of?
monoamines
64
What is the lifecyle of a neurotransmitter?
Synthesis, storage, release, receptor, neurotransmitter activation, broken down or re-uptaken.
65
Gasotransmitters include?
NO, CO, H2S
66
What type of signalling are gasotransmitters important in?
Paracrine
67
What does hierachy mean in terms of intracellular signalling?
There is a specific order in which to transmit a signal
68
Amplification is mainly at what levels?
G-protein, enzyme and protein kinase levels
69
The toxin of what illness prevents gtpase activity and so gdp remains bound to Gs and is in the "on" state
Cholera toxin
70
The toxin of this illness prevents inhibition of cyclic AMP production. resulting in what?
Pertussis toxin results in the increase in cAMP
71
How does an increase in cAMP cause whooping cough?
Increase in insulin production, greater sensitivity to histamine and a cough!
72
More cAMP in the epithelia of the intestines cause cholera via what mechanism?
Secretion of chloride hence more water into lumen and diarrhoea.
73
Famous phosphodiesterase inhibitor?
Viagra Sildenafil
74
What do protein kinases do?
Transfer a phosphate group from an ATP to Ser/Tyr/thr

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