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bm210 biochemistry > B4 lipids > Flashcards

B4 lipids Flashcards

1
Q

what is the structure of a phospholipid

A

2 fatty acids joined to a glycerol mol with a phosphate and an alcohol tail

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2
Q

phosphatidylinositol (P1)

A

precursor of signalling mols

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3
Q

phosphatidylserine (P2)

A

a key eat me signal in apoptosis

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4
Q

phosphatidylcholine (PC)

A

structural component of membranes

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5
Q

phosphatidylethanolamine (PE)

A

donor of functional groups to some membrane anchored proteins; structural roles, regulates curvature

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6
Q

sphingomyelin

A

parent sphingolipid
a precursor of some signalling mols, involved in lipid rafts

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7
Q

cholesterol

A

can be as much as % of membrane lipid
key in regulating fluidity and permeability
involved in lipid rafts

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8
Q

each glycerophospholipid is a class with variations in what side chains

A

fatty acyl

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9
Q

fatty acids can be saturated or saturated
what does this mean

A

saturated (no double bonds)
unsaturated (double bonds)

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10
Q

how many Cs long is a fatty acid

A

12-22

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11
Q

lipids are amphipathic
what does this mean

A

have both hydrophobic and philic regions
in this case a hydrophobic tail and a polar head group

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12
Q

what does it mean for a membrane to be described as fluid

A

they accommodate protein conformational changes without loss of integrity

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13
Q

certain signals catalyse the breakdwon of Ptdlns (4,5)P2 into what

A

inositol triphosphate and diacylglycerol
both are key intracellular messengers

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14
Q

GPL biosynthesis is via what pathway and where

A

phosphatidate and within the ER

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15
Q

what is de novo glycerophospholip synthesis

A

combination of activated alcohol (headgroup) with diacylglycerol

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16
Q

what cellular lipid is a major component of lung surfactant

A

PC

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17
Q

what does PC normally maintain

A

surface tension of fluid to keep alveoli open

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18
Q

what does low PC result in

A

collapse of alveoli

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19
Q

what is respiratory distress syndrome and who does it affect

A

often premature babies
laboured breathing blue fingers/toes

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20
Q

how is respiratory distress syndrome treated

A

ventilation (O2) and artificial surfactant

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21
Q

what is ceramide

A

precursor for sphingomyelin (the major sphingolipid

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22
Q

what is ceramide synthesised from

A

synthesised from serine and palmitoyl-CoA

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23
Q

how are sphingolipids further modified

A

addition of sugars

24
Q

what are gangliosides

A

important in cell surface mols
highly prevalent in nervous tissue

25
what is a disease involving gangliosides
tay sachs disease
26
what does tay sachs disease involve
an inherited disorder affects motor function, then vision, fatal by 3 years can be diagnosed during pregnancy no treatment available
27
what causes tay sachs disease
inability to degrade gangliosides (normally happens in lysosomes) lysosomes (esp in neurons) fill with gangliosides
28
what is sphingosine phosphorylated by and what does it produce
by sphingosine kinase generating sphingosone 1-phosphate a key signalling mol
29
what is cholesterol
an essential component of membranes helps maintain membrane bilayer integrity and regulates permeability
30
what is cholesterol a precursor of
steriods, vitamins, and bile salts
31
what is excess cholesterol associated with
cardiovascular disease
32
what does cholesterol biosynthesis use
acetyl CoA
33
3 steps of cholesterol biosynthesis
1. synthesis of isopentyl pyrophosphate (via mevalonate) the building block of cholesterol 2. condensation of 6 mols of isopentyl pyrophosphate to form squalene 3. cyclisation of squalene and further processing to cholesterol
34
how much does the rate of cholesterol synthesis vary and what is it dependent on
700 fold depending on how much is in the diet
35
the rate of synthesis is responsive to how much cellular cholesterol is present what is this mechanism
feedback regulation
36
what is the major site of cholesterol synthesis and site of significant synthesis
liver intestines
37
what regulates cholesterol synthesis
HMG-CoA reductase (integral membrane protein in the ER)
38
how does HMG-CoA reductase regulate cholesterol synthesis
catalyses the committed step of cholesterol synthesis its amount its activity
39
what are the 4 ways in which HMG-CoA reductase is controlled
-rate of synthesis of HMG-CoA reductase mRNA -rate of translation of HMG-CoA reductase mRNA to protein -rate of degradation of HMG-CoA reductase protein -phosphorylation state of HMG-CoA reductase protein
40
what transcription factor is used in the transcriptional regulation of HMG-CoA reductase
SREBP sterol regulatory element binding protein
41
what is SRE (sterol regulatory element) in transcriptional regulation of HMG-CoA reductase
region of HMG-Coa reductase gene to which DNA binding domain of SREBP binds
42
what is the rate of translation of HMG-CoA reductase mRNA to protein inhibited by
nonsterol metabolites derived from mevalonate
43
what senses increasing levels of sterols
HMG-CoA reductase membrane domain
44
after increasing levels of sterols have been detected the membrane domain indirectly acts with what and what is the result
ubiquitinating enzymes HMG CoA reductase becomes polyubiquitinated
45
after HMGCoA red becomes polyubiquitinated what happens
is extracted from membrane and degraded by the proteasome
46
what does phosphorylation do to the catalytic activity of HMGCoA red
decreases
47
what is phosphorylation carried out by in regulation of HMG CoA reductase
AMP activated protein kinase
48
what does phosphorylation of HMG-CoA red do to cholesterol synthesis
stops it
49
how is cholesterol transported throughout the body and their structure
in body fluids in lipoprotein particles hydrophobic lipid core, surrounded by polar lipids and proteins
50
what is the good cholesterol
HDL (high density lipoprotein
51
what is the bad cholesterol
LDL (low density lipoprotein)
52
what are bile salts, where are they synthesised and stored
-detergents (solubilise dietary lipids) -synthesised in liver -stored in gall bladder and released into small intestine
53
what are the 5 classes of steroid hormones
-progestagens -glucocorticoids -mineralcorticoids -androgens -oestogens
54
what are statins
HMG-CoA reductase inhibitors act as lipid lowering drugs to reduce cholesterol
55
when are statins prescribed
if patient has at least one risk factor for coronary heart disease
56
what are the 3 statins regularly prescribed
atorvastatin fluvastatin lovastatin

bm210 biochemistry (19 decks)

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