Quiz 7 Flashcards
(152 cards)
What things make fatty acids good for energy substrates and storage?
They are highly reduced, inert, they pack tightly together, hydrophobic (so they do not affect they osmolarity of the cell)
Do chylomicrons transport triglycerides or free fatty acids? What about albumin?
Chylomicrons transport triglycerides.
Albumin transports free fatty acids.
What occurs when a chylomicrons reaches its target location? What enzyme is involved?
ApoC-II (on the chylomicron) activates lipoprotein lipase. Lipoprotein lipase breaks down the chylomicrons and converts the triacylglycerols to FA and glycerol which can then be taken up by the tissue
Where are chylomicrons synthesized?
In the ER of Enterocytes (absorptive small intestine cells)
What are apolipoproteins?
They are proteins that bind to lipids to form lipoproteins. They serve diverse functions such as activating enzymes and receptors.
Is a chylomicron a lipoprotein or an apolipoprotein?
Lipoprotein. Apolipoproteins are just associated with lipoproteins
What are the four classes of lipoproteins? What are their relative sizes?
Chylomicrons (extra large)
VLDLs (large)
LDL (Medium)
HDL (small)
Which lipoproteins contain the most protein? (In descending order)
1) HDL
2) LDL
3) VLDL
4) Chylomicron
Which lipoproteins contain the most triglycerides in descending order?
1) chylomicron
2) VLDL
3) LDL
4) HDL
Are lipoproteins composed of a mono layer or a bilayer?
Monolayer of phospholipids
Which lipoprotein contains the most cholesterol (in descending order)?
1) LDL
2) HDL
3) VLDL
4) Chylomicron
What happens to the chylomicron after it has dumped off its lipids in the target tissue?
The chylomicron remnants go back to the liver. This is where the endogenous pathway begins
The liver produces what lipoprotein to deliver fatty acids to the tissues? What happens after? (Two things)
VLDL.
After VLDL dumps off its fatty acids to the tissue, it becomes LDL. The LDL can either go back to the liver to recycle back to VLDL orrrr it can dump off their excess cholesterol to macrophages in the vasculature.
What does HDL do?
HDL takes up the cholesterol obtained in the macrophages (foam cells) and delivers the cholesterol back to the liver.
Explain how lipoproteins are internalized by target tissue cells. (5 steps)
1) LDL receptor binds to apoB-100 on lipoprotein
2) LDL is internalized in endosome
3) LDL receptors segregate from vehicle and recycled to surface
4) endosome fuses with lysosome
5) enzymes in lysosome break down LDL into aa, FA, and cholesterol
Where is perilipin located? What is its function?
It is located on the surface of lipid droplets in adipose cells. Perilipin functions to stabilize the lipid droplet.
What does perilipin do once it is phosphorylated by PKA?
It will activate CGI (compatible gene indicator)
What does CGI do once it is activated?
Comparative gene indicator will go on to phosphorylate ATGL (adipose triglyceride lipase)
What does ATGL do once activated?
It will break up triacylglycerols into diacylglycerides and monoacylglycerides.
What two things does PKA do in an adipose cell?
Phosphorylates perilipin
Phosphorylates hormone sensitive lipase (HSL)
What does HSL (hormone sensitive lipase) do once phosphorylated?
HSL will break diacylglycerides down to monoacylglycerides
What is the role of MGL (monoglyceride lipase)?
MGL removes glycerol from monoacylglycerides to form free fatty acids. The free fatty acids can then be taken up in the blood.
Once fatty acids are released into the blood, they are transported by ___ and taken up into cells via ____
1) serum albumin
2) fatty acid transporters
How is glycerol catabolized? What is it turned into? What is produced in the process?
It will be converted into Glyceraldehyde-3- phosphate to enter glycolysis. In this process, you use 1 ATP and create one NADH