Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

BQ II > T6. PLASMA LIPOPROTEIN METABOLISM > Flashcards

T6. PLASMA LIPOPROTEIN METABOLISM Flashcards

(88 cards)

Start Studying
1
Q

What is a lipoprotein?

A

A lipoprotein is a macromolecular complex of proteins (apolipoproteins or apoproteins)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the structure of lipoproteins?

A

Lipoproteins are spherical

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How are lipoproteins classified?

A

Lipoproteins are classified by density: (+) volume = (-) density. Order: Chylomicrons > VLDL > IDL > LDL > HDL.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How does TAG concentration vary with lipoprotein volume?

A

TAG concentration increases with volume.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How does protein concentration vary with lipoprotein density?

A

Protein concentration increases with density.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the lipid-to-protein proportion in lipoproteins?

A

The lipid and protein proportion are approximately 50:50.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the specific function of chylomicrons?

A

Transport of exogenous lipids.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the specific function of VLDL?

A

Transport of endogenous lipids.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the specific function of LDL?

A

Transport of cholesterol from liver to tissues (regulation); contains higher proportion of cholesterol.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the specific function of HDL?

A

Transport of cholesterol from tissues to the liver.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What happens to dietary lipids?

A

Dietary lipids are packaged into chylomicrons that transport TAG through capillaries.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What happens to chylomicrons during circulation?

A

LPL releases TAG content to adipose and muscle tissues during transit; chylomicron remnants are taken up by the liver.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How are endogenous lipids delivered?

A

Endogenous lipids and cholesterol from the liver are delivered to adipose and muscle tissue by VLDL.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What happens to VLDL in circulation?

A

VLDL gradually converts to LDL

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How does the liver handle lipoproteins?

A

The liver takes up LDL

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How is excess cholesterol from tissues handled?

A

Excess cholesterol in extrahepatic tissues is transported back to the liver as HDL.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What happens to cholesterol in the liver?

A

In the liver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Why is cholesterol esterification important?

A

Cholesterol esterification helps mitigate atheroma risk by producing non-harmful cholesterol esters.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are apolipoproteins?

A

Apolipoproteins are proteins involved in structural functions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is recognized by the LDL receptor?

A

The LDL receptor recognizes remnant chylomicrons (apoE)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the function of APO AI?

A

Structural function and activator of LCAT.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Which lipoprotein contains APO AI?

A

HDL.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the function of APO B48?

A

Transport

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Which lipoprotein contains APO B48?

A

Chylomicrons.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What is the function of APO B100?
Structural function and ligand for LDL receptor.
26
Which lipoproteins contain APO B100?
LDL and VLDL.
27
What is the function of APO CII?
Activator of LPL.
28
Which lipoproteins contain APO CII?
Chylomicrons
29
What is the function of APO E?
Ligand for LDL receptor and Apo E receptor.
30
Which lipoproteins contain APO E?
Chylomicrons
31
What is the function of lipoprotein lipase (LPL)?
Hydrolysis of TAG and phospholipids in chylomicrons and VLDLs.
32
Where is LPL found?
In adipose tissue and muscle.
33
What is the function of hepatic lipase (HL)?
Hydrolysis of TAG and phospholipids in VLDL
34
Where is HL found?
Liver.
35
What is the function of LCAT?
Esterification of HDL with fatty acids from phosphatidylcholine.
36
Where is LCAT produced?
Liver.
37
What is the function of CETP?
Cholesteryl ester and TAG exchange between HDL and APO B-containing lipoproteins.
38
What is the function of PLTP?
Phospholipid and cholesterol transfer from TAG-rich lipoproteins to HDL.
39
What pathway do chylomicrons follow?
Chylomicrons transport cholesterol and TAG from diet in an exogenous pathway.
40
Where are chylomicrons assembled?
In the ER of enterocytes in an apoB-48-dependent process.
41
How do chylomicrons acquire APO E and APO C-II?
They acquire apoE and apoC-II from HDL.
42
What activates LPL on capillary endothelial cells?
ApoC-II activates LPL on the surface of capillary endothelial cells.
43
What is the function of LPL on chylomicrons?
LPL hydrolyzes TAGs into fatty acids for export to other tissues.
44
What happens to chylomicrons after TAG hydrolysis?
They become chylomicron remnants with reduced TAGs and without apoC-II.
45
How do hepatocytes recognize chylomicron remnants?
Through apoE and LDL (regulable) and LRP (nonregulable) receptors.
46
What happens to chylomicron remnants after recognition by hepatocytes?
Remnants are endocytosed by hepatocytes
47
Why is the clearance of chylomicron remnants important?
It ensures efficient transport and utilization of dietary fats and cholesterol.
48
How is lipid level regulation maintained during chylomicron clearance?
By regulating the expression of lipid receptors.
49
What is the function of VLDL metabolism?
VLDL transports cholesterol and TAG synthesized de novo to extrahepatic tissues via an endogenous pathway.
50
Where are cholesterol and TAG synthesized?
In the endoplasmic reticulum (ER) of hepatocytes.
51
What is the secretion of VLDL dependent on?
ApoB-100 and fatty acid availability.
52
What apolipoproteins do VLDL acquire from HDL?
ApoE and apoC-II.
53
What happens to VLDL in the bloodstream?
TAGs are hydrolyzed by LPL on the surface of capillary endothelial cells.
54
What activates LPL in VLDL metabolism?
ApoC-II.
55
What is formed after VLDL is hydrolyzed?
IDL (VLDL remnants) are formed.
56
What are the fates of IDL?
IDL can release FA to form LDL or be taken up by hepatocytes via LDL receptors.
57
Which apolipoproteins do LDL receptors recognize in IDL?
ApoE or ApoB-100.
58
What is the function of LDL metabolism?
Transport of cholesterol to extrahepatic tissues via an endogenous pathway.
59
How is LDL formed?
From IDL by the action of hepatic lipase
60
What else does LDL acquire?
Esterified cholesterol taken up from HDL.
61
How do extrahepatic tissues take up LDL?
By endocytosis mediated by apoB-100 and LDL receptors.
62
How long can LDL remain in circulation?
Some LDL can remain in circulation for days.
63
What can happen to LDL in circulation?
It can be oxidatively modified
64
How do oxidized LDL particles contribute to disease?
They can adhere to endothelium and be taken up by macrophages
65
What initiates control of intracellular cholesterol levels?
LDL binds to apoB-100 in a clathrin-coated pit
66
What happens in the endosome during LDL processing?
LDL dissociates from its receptor (at acidic pH)
67
What happens when the endosome fuses with lysosomes?
ApoB-100 is degraded and cholesteryl esters are hydrolyzed.
68
What is the fate of released cholesterol?
Used for membrane synthesis or other cellular needs.
69
What mechanisms regulate cholesterol levels?
Autoregulation via enzyme activity
70
How does cholesterol regulate its own synthesis?
By reducing [HMG-CoA reductase]
71
How is cholesterol stored?
Via activation of ACAT
72
How does cholesterol affect LDL receptor levels?
It represses the transcription of LDL receptors to reduce uptake.
73
What is the function of HDL metabolism?
Reversible transport of peripheral cholesterol to the liver.
74
Where is HDL synthesized?
In the liver and small intestine as nascent HDL.
75
What are the major components of nascent HDL?
ApoA-I and LCAT.
76
How does HDL collect cholesterol?
From cell membranes and intracellular sites via ABCA1
77
What is mature HDL called?
HDL2
78
What enzymes recycle mature HDL?
Hepatic and endothelial lipase.
79
What happens during HDL recycling?
Cholesterol is effluxed to the liver to form new discoidal HDL.
80
How can HDL deliver content to the liver without endocytosis?
Through SR-B1 receptor-mediated transfer.
81
How is HDL endocytosed?
HDL containing apoE can be taken up by LDL receptors.
82
Where does HDL degradation occur?
In the liver and kidney via endocytosis.
83
Why must cholesterol transport and synthesis be coordinated?
To avoid overaccumulation and abnormal deposition of cholesterol.
84
What are the three levels of cholesterol synthesis regulation?
HMG-CoA reductase activity
85
How is HMG-CoA reductase activity regulated?
Allosterically by cholesterol concentration
86
How is the expression of HMG-CoA reductase regulated?
By the level of intracellular cholesterol.
87
What inhibits LDL receptor synthesis?
An increase in cholesterol concentration.
88
How is the rate of cholesterol esterification regulated?
By phosphorylation and long-term control mechanisms.

BQ II (17 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions