Valencik Lipid Metabolism Flashcards
What are the four pathways of lipid transport?
1) Food → Any Tissue
2) Liver → Other Tissues
3)Other Tissues → Liver
(reverse transport)
4)Adipose Tissue → Other Tissues
(blank) levels are higher than blood glucose and vary with dietary intake.
plasma lipid
What do free fatty acids look like?
R-COOH
Where do we find FFAs and how do they work?
stored in adipose-> mobilized to provide energy to other tissues-> travel in blood and NONCOVALENTLY attached to alubmin
What do we need to do with TAGs and what are the two types?
we need to either store them or use them
dietary and synthesized
Where do we get cholesterol?
we get it from our diet
made by most tissues
What is the storage form of cholesterol?
cholesterol esters (CE)
(blank) are lipids with a hydrophilic phosphate head group.
phospholipids
(blank) are the mode of transport for lipids.
lipoproteins
What are macromolecular assemblies of protein and lipid aggregates?
lipoproteins
What is the protein component of a lipoprotein called and what is special about this?
an apolipoprotein
It is amphipathic
What can the lipid component of a lipoprotein be?
TAG, FFA, cholesterol, cholesterol esters, phospholipids, other lipids and their derivatives
Which of these are hydrophobic: TAGs Cholesterol esters Free cholesterol Phospholipid
TAGs
cholesterol esters
Plamsa liporpteins can be separated by (blank).
The more lipids the (blank) the lipoprotein.
electrophoresis
lighter
When doing electrophoresis, which kinds of lipoproteins wouldnt really move?
What lipoproteins would move very far?
heavy, large lipoproteins with mostly nonpolar lipids such as chylomicrons
alpha-lipoproteins (HDL)
Put these lipoproteins in order form biggest to smallest.
HDL, VLDL, LDL, Chylomicrons
Chylomicrons, VLDL, LDL, HDL
What are these the normal ranges for (mg/dL): 400-800 40-280 120-280 65-200 30-90 125-275 8-25
TOtal lipid: 400-800 Triglycerides: 40-280 Total cholesterol: 120-280 LDL: 65-200 HDL: 30-90 Phospholipids: 125-275 FFAs: 8-25
What makes up 70% of plasma cholesterol
LDL cholesterol
What is always bound to albumin?
FFAs
What all does total cholesterol include?
both cholesterol and cholesterol esters
Where do you find the majority of triglycerides?
in VLDLs
Where do we make chylomicrons and what percentage of chylomicrons are made up of TAGs?
Intestine
86% (contains the highest amount of TAGs)
Where do we make LDL and what percentage is made up of cholesterol esters and cholesterol?
From VLDL and IDL
40% cholesterol esters and 8% cholesterol
What has the highest fraction of total cholesterol?
LDLs
When fasting, where are the most TAGs found?
in VLDLs
When fasting, where is the most cholesterol found (C + CE)?
LDL
Digestion and absorption of dietary lipids occur in the (blank).
small intestine
Once you get micelles into the small intestine, what degrades triglycerides?
intestinal lipases
When you have TAGs in the small intestine, what do they combine with and what do they become?
combine with cholesterol and apolipoproteins into chylomicrons
Chlyomicrons move through the (blank) and bloodstream to tissues.
lymphatic system
What converts TAGs to fatty acids and glycerol?
lipoprotain lipase (activated by ApoC-II) in the capillary
Once you have your broken down TAGs into glycerol and fatty acids where do they go?
enter cells where they can be oxidizes as fuel or reesterified for storage
Digestion and absorption of dietary lipids occur in the small intestine, after reassembly in the enterocytes the TAGs are packaged into (blank) and delivered to (blank and blank) tissues (primarily).
chylomicrons
muscle and adipose
(Blank) are not used by the brain or liver (they dont have LPL (lipoprotein lipase))
chylomicrons
Do fatty acids and glycerol get taken up by the lactating mammary, spleen, lungs, kidney, endocrine glands and aorta?
yes
dietary triglycerides undergo variable degrees of (blank) in the intestinal lumen.
hydrolysis
Medium and short fatty acids are absorbed as such into the (Blank)
portal blood
Free fatty acids are activated by (blank) prior to TAG assembly.
acyl-CoA synthetase
Long-chain fatty acids are reassembled into (Blank) in the ER then incorporated into chylomicrons.
TAGs
What happens to Long-chain fatty acids?
turns into TAGS and put into chylomicron
Do enterocytes possess glycerol kinase, what does this mean for enterocytes?
no
This means they cannot they cannot metabolize the glycerol produced during triacyl glycerol degradation. This glycerol is instead shuttled to the liver
What is the life span of chylomicrons in the plasma? What is the life span of TAGs?
less than 1 hour
5-10min
Where do we find B-48?
only on chylomicrons!!!
TAGs are reassembled and chylomicrons are formed in the (blank) of the intestinal mucosa
endoplasmic reticulum
What are the three roles of apolipoproteins?
1) regulate plasma lipid metabolizing enzymes
2) facilitate lipid transfer
3) mediate endocytosis
Explain the journey that TAGs take?
Tags get reassembled in enterocytes->put into chlymicrons->chylomicrons enter lymphatic system-> chylomicrons transport TAGS and Cholesterol to rest of the body
Apolipoproteins have are hydrophobic or hydrophilic?
amphipathic actually
What are these:
apoB-48 and apoA-I, -A-II and IV.
apolipoproteins
Once chylomicrons enter the blood, what do they need and where do they get it from?
they need apoC-11 and apoE from plasma HDLs
How do we get the TAGs out of the chylomicrons?
lipoprotein lipase (LPL)
What is lipoprotein lipase (LPL) activity dependent on?
apoC-II
During TAG hydrolysis done by LPL, what apolipoproteins peel off the surface of the chylomicron and where do they go?
A and C
transferred to HDL
You cant just place the apolipoproteins from the chylomicrons to HDL, instead you need a special protein which is…….?
phospholipid transfer protein
SO you have a chylomicron, it gets its TAGs ripped out by LPL and then all the A and C apolipoproteins fall off….. now what happens to your chylomicron, does it keep getting beat up by LPL or does it finally get to relax?
since apoC is what activated LPL, and it just fell off, LPL can no longer beat up the chylomicron
Where do we find LPL? Where do we have no LPL?
Have: skeletal, cardiac, adipocytes
Don’t Have: liver, brain
Food consumption increases (blank) on adipocytes but decreases this expression on skeletal and cardiac muscle. Why is this important.
LPL
ensures that dietary fat is stored in well-fed state but will be used by cardiac and skeletal muscle during fasting.
(blank) detaches from LPL from the capillary membrane
heparin
THe chylomicron remnant that has been stripped of A and C apoplipoproteins and TAGS, what is left in it?
cholesterol esters, apoE and apoB-48 and left over TAGS
What happens to the chylomicron remnant?
The apo E on the chylomicron gets bound by an Apo E dependent receptor that drags the whole thing to lysozomes for degradation in the liver
Overall, dietary cholesterol ends up in the (Blank)
liver
(blank) function to deliver dietary triglycerides to adipose tissue and muscle and dietary cholesterol to the liver.
chylomicrons
What are these:
C→ free cholesterol CE→ cholesterol ester HDL→ high-density lipoprotein LPL→ lipoprotein lipase PL→ phospholipid TG→ triglyceride
things that interact with chylomicrons
In the liver, excess carbs and fats are used to synthesize (Blank and blank)
TAGs and lipids
In the liver, TAGs, lipids and cholesterol are packaged into (blank) by the ER and golgi.
VLDLs
VLDLs are (blank) into the blood circulation for delivery to extra-hepatic tissues.
exocytosed directly
Explain the process of creating and transporting TAGs in the liver?
carbs and fats are turned into TAGS-> TAGs, lipids and cholesterol are packaged into VLDLs by ER and Golgi-> VLDLs are exoctyosed into blood for delivery to other tissues-> free fatty acids from TAGs are eventually used for beta oxidation