Lecture 9 - Lipoprotein Metabolism Flashcards

(46 cards)

1
Q

why do fats need to be packaged and kept soluble

A

so they can be transported in the blood

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2
Q

what is the role of O-acyltransferase enzymes

A

transferring an acyl (fatty) acid group

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3
Q

what form is cholesterol most commonly found in

A

most commonly found in the form of cholesterol ester which is when there is a fatty acid attached

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4
Q

what will inhibit the cholesterol synthesis pathway

A

if there is a lot of cholesterol coming from the diet

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5
Q

what enzyme is inhibited to inhibit the cholesterol synthesis pathway

A

HMG CoA reductase

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6
Q

what does HMG CoA reductase do and why is this important

A

converts HMG CoA to mevalonate = rate limiting step of cholesterol synthesis pathway

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7
Q

where is cholesterol found

A

in the plasma membrane

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8
Q

what does cholesterol control in the plasma membrane

A

the fluidity of the membrane

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9
Q

what is the dietary source for cholesterol

A

animal products

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10
Q

what is cholesterol the precursor for

A

steroid hormones, bile acids and vitamin D

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11
Q

what is cholesterol a major constituent of

A

lipoproteins

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12
Q

what is cholesterol important for the transport of

A

fat soluble vitamins

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13
Q

how is cholesterol important for neuronal function

A

its a part of the myelin sheath

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14
Q

what encapsulates lipids in the structure of plasma lipoproteins

A

proteins and phospholipids encapsulate the lipids to keep the soluble

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15
Q

what are the 4 main classes of lipoproteins

A
  • chylomicrons
  • very low density lipoprotein
  • low density lipoprotein
  • high density lipoprotein
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16
Q

what is a characteristic of chylomicrons

A

triglyceride rich

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17
Q

what is a characteristic of very low density lipoprotein

A

triglyceride rich

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18
Q

what is a characteristic of low density lipoprotein

A

cholesterol rich

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19
Q

what is a characteristic of high density lipoprotein

A
  • cholesterol rich
  • densest because of the high protein content
20
Q

what do ApoB48 (chylomicrons) and ApoB100 (VLDL) and MTP play a crucial role in

A

lipoprotein assembly

21
Q

in the endoplasmic reticulum what is added to ApoB by MTP as it is being made and what does this form

A

lipids are added to ApoB and this forms a small lipopotein

22
Q

when a small lipoprotein particle is formed from lipids being added to ApoB, what does MTP add to make the particle bigger

A

triglycerides

23
Q

what occurs in the golgi before ApoB is secreted

A

glycosylation

24
Q

lipids combine with what via MTP in the ER to form chylomicrons

25
where are chylomicrons secreted from and what do they enter
from intestinal cells entering the bloodstream and lymphatic system
26
what gives plasma a milky appearance after a fat rich meal and what is this due to
chylomicrons can give plasma a milky appearance due to high triacylglycerol content
27
chylomicrons and VLDL are metabolised similarly by what
by lipoprotein lipase
28
what does lipoprotein lipase do and where does this occur
hydrolyses the fatty acids, this occurs at the surface of tissues
29
what does hepatic lipase (HTGL) do
generates LDL
30
what dies LRP bind to
apoE
31
what does LDLR bind to
apoB
32
what receptor family are LRP and LDLP members of
LDL receptor family
33
what do LRP and LDLP do
take up remnant IDl and LDL particles
34
what is the function of lipoproteins
solubilise lipids for transport in blood to tissues
35
what apoprotein is important for assembly
apoB
36
what apoproteins are important for ligand cell surface receptors
apoB and apoE
37
what apoprotein is important for enzyme cofactors
apoCII (for lipoprotein lipase)
38
what are factors that affect lipids levels
- diet = saturated vs unsaturated fats - drugs = fibrates and statins - genetics = defects in lipid metabolism - disease = diabetes
39
diets rich in what are LDL cholesterol lowering
diets rich in plant sterols
40
what are mediterranean diets found to reduce
cardiac mortality
41
eating high amounts of saturated fats can do what
cause LDL levels to increase
42
what do statins do to LDL cholesterol
lower intracellular levels so the body makes more receptors meaning there is more LDL uptake
43
what does ezetimibe do to LDL cholesterol
less cholesterol coming into the body as decreased intestinal uptake, so more LDL receptors
44
fibrates and PUFAs both activate a what and what does this bind to and what does this switch on (example)
transcription factor, binds to response element and switching on many genes one of these is lipoprotein lipase which hydrolyses VLDL and chylomicrons
45
what would a defect in LPL or apoC-II cause
elevated triglyceride levels
46
what would a defect in apoB or MTP cause
low blood cholesterol levels