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Block 3 Week 4 Meg > Valencik: Lipid transport > Flashcards

Valencik: Lipid transport Flashcards

1
Q

4 pathways of lipid transport

A

Food –> any tissue
Liver –> other tissues
Other tissues –> liver
Adipose tissue –> other tissues

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2
Q

What gets transported in lipid transport?

A 
Free fatty acids
Triglycerides
Cholesterol
Cholesterol esters
Phospholipids
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3
Q

Plasma lipid level are higher than blood (blank) and vary with dietary intake

A

glucose

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4
Q

Stored in adipose tissue, mobilize to provide energy to other tissues. Travel in the blood stream noncovalently attached to albumin.

A

free fatty acids

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5
Q

(blank) TAGs need to be used or stored. (blank) TAGs need to be used or stored.

A

dietary; synthesized

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6
Q

Storage form of cholesterol

A

cholesterol esters

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7
Q

Lipids with a hydrophilic phosphate head group

A

phospholipids

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8
Q

Macromolecular assemblies of protein and lipid aggregates

A

Lipoproteins

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9
Q

What is the protein component called in a lipoprotein?

A

apolipoprotein

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10
Q

What does the lipid component of the lipoprotein include?

A

TAGs, free fatty acids, cholesterol, cholesterol esters, phospholipids, other lipids and their derivatives

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11
Q

Two components of the lipoprotein that are amphipathic?

A

apolipoprotein and phospholipid monolayer

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12
Q

Two components of the lipoprotein that are hydrophobic?

A

cholesterol ester and triglyceride

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13
Q

When plasma lipoproteins are separated by electrophoresis, which component travels the least? What travels the furthest?

A

chylomicrons travel the least, HDL travels the most. LDL and VLDL travel in between.

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14
Q

During electrophoresis of lipoproteins, protein/lipid ratio determines how far each lipoprotein travels. If it has more lipids, it will be (blank) and travel (blank).

A

lighter; further

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15
Q

Chylomicrons and VLDLs are both very (blank). Which one is about 1micrometer in diameter? Which one is about 10-80nm in diameter?

A

hydrophobic; chylomicrons; VLDLs

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16
Q

LDLs and HDLs are much smaller in diameter than (blank)

A

chylomicrons

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17
Q

Chylomicrons have a high (blank) ratio

A

volume/surface

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18
Q

HDLs are (blank) rich and dense

A

protein

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19
Q

When fasting, where are most triglycerides found?

A

VLDLs

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20
Q

What makes up about 70% of plasma cholesterol when fasting?

A

LDL cholesterol

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21
Q

What are free fatty acids bound to?

A

albumin

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22
Q

Chylomicrons are only present when you’ve eaten a (blank) meal

A

fatty

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23
Q

(blank) contain the highest fraction of TAGs

A

chylomicrons

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24
Q

(blank) have the highest fraction of total cholesterol

A

LDLs

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25
When fasting, where are the most TAGs found?
VLDLs
26
When fasting, where is the most cholesterol found?
LDL
27
1. Fat is ingested in the diet and bile salts emulsify dietary fats in the small intestine forming mixed (blank)
micelles.
28
2. Intestinal lipases degrade (blank)
TAGs
29
3. Fatty acids and other breakdown products are taken up by the intestinal mucosa and converted into (blank)
TAGs
30
4. TAGs are incorporated, with cholesterol and apolipoproteins, into (blank)
chylomicrons
31
5. Chylomicrons move through the (blank) and bloodstream to the tissues.
lymphatic system
32
6. Lipoprotein lipase, activated by (blank) in the capillary, converts TAGs to fatty acids and glycerol.
apoC-II
33
7. (blank) enter cells
Fatty acids
34
8. Fatty acids are (blank) as fuel or (blank) for storage
oxidized; reesterified
35
So, when we eat triglycerides, we start with a TAG that is digested by (blank) to produce free fatty acid and diacylglycerol. The DAG is taken to a MAG.
pancreatic lipase
36
Monoacylglycerol can enter the enterocyte where it can be acted on by (blank) to form new TAGs that can be repackaged to make new chylomicrons.
Acyl-CoA synthase
37
Life span of a chylomicron
<1 hour
38
3 Roles of apolipoproteins
1. regulate plasma lipid metabolizing enzymes 2. facilitate lipid transfer 3. mediate endocytosis
39
Chylomicrons are exocytosed into the lymphatic system and transport these two things to the rest of the body
"dietary" cholesterol and TAGs
40
This apolipoprotein is only found on chylomicrons
ApoB-48
41
From where do chylomicrons acquire additions apolipoproteins in the blood? What are some of these apolipoproteins?
From HDLs; apoC-II and apoE
42
Chylomicrons want to dump their TAGs. Once they acquire apoC-II, they can bind to (blank) and hydrolyze 80-90% of TAGs. While doing this, they can also recycle some of their apos back to (blank)
lipoprotein lipase; HDL
43
Activity of LPL is dependent on (blank)
apoC-II
44
During TAG hydrolysis, surface phospholipids and apolipoproteins A and C peel off the surface and are transferred to HDL. This leaves behind a chylomicron (blank)
remnant
45
Chylomicron remnants, containing primarily (blank), apoE and apoB-48, are taken up by, the liver through interaction with an apoE dependent receptor.
cholesterol esters
46
How do lipids get transported from the liver to other tissues that need them?
VLDLs
47
In the liver, excess carbohydrates and fats are used to synthesize (blank) and lipids
TAGs
48
TAGs, lipids, and cholesterol are packaged into (blank)
VLDLs
49
VLDLs are exocytosed (blank) into the blood and delivered to extra-hepatic tissues
directly
50
The free fatty acids from TAGs are stored or used to produce energy through (blank)
B-oxidation
51
Like chylomicrons, VLDLs quickly obtain (blank) and (blank) and additional cholesterol esters from HDLs.
apoCs and apoEs
52
What is apo are "nascent" VLDLs born with?
ApoB-100
53
What's the lifespan of VLDLs?
< 1 hour
54
What's the difference between ApoB48 found on chylomicrons and ApoB100 found on VLDLs? What is this an example of?
Encoded by the same gene, but apoB-100 is much longer; tissue-specific RNA editing
55
In the (blank), the RNA is post-transcriptionally altered and has a STOP codon early on to generate a shorter apo than in the liver.
intestine
56
VLDL travels down a similar path to chylomicrons but (blank) is slower
hydrolysis
57
Similar to chylomicrons, lipoprotein lipase frees FAs into the tissue and is coupled to the loss of apolipoproteins to (blank)
HDL
58
These are generated as VLDLs lose their apoCs to HDL
IDL
59
VLDLs acquire more cholesterol esters from HDLs through the activity of this protein
CETP
60
Two types of VLDL remnants. 50% contain lots of (blank) and are endocytosed by the liver. Smaller ones become (blank) on their way to becoming LDLs.
apoE; IDLs
61
What enzyme is attached to hepatocytes via heparin and takes IDLs to LDLs?
hepatic lipase
62
Hepatic lipase, unlike lipoprotein lipase, is independent of (blank)
apoC-II
63
LDLs are (blank)% cholesterol esters and (blank)% phospholipids and only carry this apolipoprotein.
40%; 20%; apoB-100
64
Lifespan of LDLs
3 days
65
What fraction of LDLs can bind to hepatocytes and be endocytosed? What fraction cannot?
2/3; 1/3
66
3 things can happen if LDLs are providing excess intracellular cholesterol
1. ACAT creates cholesterol esters for storage 2. HMG-CoA reductase transcription repressed 3. LDL receptor transcription repressed
67
If LDLs are not cleared by LDL receptors, how are they cleared?
macrophages endocytose LDLs via scavenger receptors
68
Scaveneger receptors have a higher affinity for (blank) or (blank) LDLs
oxidized; acetylated
69
3 ways in which lipids are transferred from other tissues to the liver
1. ApoE mediated endocytosis of remnant particles containing cholesterol esters 2. CE from HDL are transferred to hepatocytes via SR-BI 3. Large HDLs with ApoEs are endocytosed
70
HDLs are released from the liver and intestine and are rich in (blank)
phospholipids
71
HDLs do not contain these two things
cholesterol; cholesterol esters
72
When made by the liver, HDLs have these apolipoproteins
apoA-I, apoA-II, apoC-I, apoC-II, apoE
73
When made by the intestine, HDLs have this apolipoprotein
apoA-I
74
HDLs are converted to (blank) and (blank)
HDL3 and HDL2
75
HDL particles dock to the cell surface through (blank) or (blank) binding. (blank) pumps free cholesterol from the cell surface into the HDL.
apoA-I; apoE; ABCA1
76
The cholesterol is processed in 2 steps. First, (blank) binds to the surface of the HDL and is activated by (blank) to catalyze the esterification of cholesterol.
LCAT; apoA1
77
...Then, once a CE is formed, (blank) transfers CEs to lipoprotein remnants or LDLs
CETP
78
So, excess cellular cholesterol is returned to the liver via lipoprotein remnants or LDLs as (blank). This occurs in an apoE dependent manner.
cholesterol esters
79
Another way cholesterol can be delivered to hepatocytes is by HDLs remaining intact but giving off C and CEs to hepatocytes via (blank) and (blank)
hepatic lipase; SR-BI
80
Finally, a few HDLs will acquire enough (blank) to be endocytosed themselves.
apoE
81
What is the key way that cholesterol is transported to hepatocytes?
CETP dependent transfer of CEs to remnants
82
Deficiency in triglyceride transfer protein. Therefore, no ApoB lipoproteins are assembled
ABlipoproteinemia
83
Absence of ABCA1 protein. Therefore apoAs can’t acquire lipids and mature HDLs don’t form.
Tangier disease
84
Absence of ApoClll (a LPL inhibitor).
Apo CIII deficiency
85
Cholesterol esters cannot be transferred to other remnants.
CETP deficiency
86
When do lipids get transferred from adipose tissue to other tissues?
during starvation
87
4 enzymes involved in glycerolneogenesis in the liver and adipose tissue
1. pyruvate carboxylase 2. malate DH 3. PEPCK 4. G3PDH
88
(blank) activity induced by thiazolidinediones
PEP Carboxykinase
89
Involved in the stimulation of human fat cell lipolysis
ATGL lipase

Block 3 Week 4 Meg (6 decks)

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