Lipid Uptake and Synthesis Flashcards
What does pancreatic lipase do?
Breaks apart triacylglycerol into 2 fatty acids and monoacylglycerol
What drug is a reversible inhibitor of pancreatic lipase?
Orlistat (OTC = xenical, alli)
What is a common side effect of pancreatic lipase inhibitory drugs? ir orlistat, xenical, alli, …
Unable to absorb fat soluble vitamins like A, D, E, and K
What are the main two functions of Cholestyramine?
Removes bile acids, which stimulates liver bile acid synthesis from cholesterol.
Stimulates LDL receptor in liver causing reduced serum cholesterol
Secretion of pancreatic enzymes occurs in response to what gut hormone?
cholecystokinin
What is the primary function of bile salts?
To aide in digestion by forming micelles to package long and very long chain fatty acids
What are the 5 major lipoproteins that enable fats and cholesterol to move within the water-based bloodstream?
chylomicrons, IDL, HDL, VLDL, LDL
Where are chylomicrons produced?
Intestinal epithelia
from dietary fat
Where are VLDLs produced?
In liver mainly from dietary CHO
Where are IDLs produced?
In the blood after Triacylglycerol digestion
VLDL remnant
Where are LDLs produced?
In the blood after triacylglycerol digestion
Remnant of IDL
End product of VLDL
Where are HDLs produced?
Liver and Intestine
What are the two major functions of HDLs?
Exchanges proteins and lipids with other lipoproteins
returns cholesterol from peripheral tissues to liver
What are the most and least dense lipoproteins?
Chylomicrons = least dense HDL = most dense
Why are certain lipoproteins more dense than others?
The ones with more proteins relative to TG are more dense
What major apolipoproteins are found in VLDLs?
B-100
C-II
E
What major apolipoproteins are found in chylomicrons?
B-48
C-II
E
What major apolipoproteins are found in LDLs?
B-100
What major apolipoproteins are found in HDLs?
A-1
C-II
E
What two apolipoproteins are encoded on the same gene? A difference in mRNA encoding determines which is produced
B-48
B-100
Where is apoB-48 produced?
intestine
Where is apoB-100 produced?
liver
What is lipoprotein lipase activated by?
ApoCII
Lipoprotein Lipase is anchored to capillary walls of most tissues by?
Heparin sulfate
What stimulates the synthesis and secretion of adipose isoenzyme of lipoprotein lipase?
insulin
Where does the synthesis of lipids primarily occur?
In the liver
How does acetyl CoA get out of mitochondria?
It is changed into citrate
What are the two major ingredients for fatty acid synthesis?
cytosolic acetyl CoA
NADPH
What is an important cofactor for acetyl CoA carboxylase?
Biotin
What does acetyl CoA Carboxylase do?
Produces Malonyl CoA from Acetyl CoA
uses ATP
What enzyme sequentially adds 2C units from malonyl CoA to the growing fatty acid chain?
Fatty Acid Synthase Complex
Oxidation of new fatty acids in mito after they are synthesized is prevented by inhibition of _________
by ___________
carnitine palmitoyltransferase (CPT1) by malonyl CoA
Where does the elongation of fatty acids occur?
ER
What organ makes especially long fatty acids?
Brain (C22 to C24)
What is the end product of fatty acid synthesis?
Palmitate (C16)
In the elongation of Fatty acids, the fatty acyl chain attached to __________ instead of ACP
Coenzyme A
Where does desaturation of fatty acids occur?
In the ER
What is required for the desaturation of fatty acids?
molecular oxygen
What is the main storage form of fatty acids?
triacylglycerols
What enzyme in the TG synthesis process is found in the liver but not in adipose tissue? converts glycerol to glycerol-3-phosphate
glycerol kinase
Fatty acid synthase makes palmitate, that can be _________ and _________
elongated
desaturated
What stimulates the synthesis and secretion of lipoprotein lipase?
Insulin
What enzyme breaks down TGs to FAs for release by adipose tissue?
Hormone sensitive Lipase
What is the key intermediate in phospholipid synthesis from fatty acids?
CDP-serine intermediate
Which fatty acid of phospholipids tends to be unsaturated?
C2 position
What is the general class of enzymes that cleave phospholipids at different locations on the molecule?
phospholipase
Phospholipase A2 cleaves phospholipids in the membrane for ________ synthesis?
prostaglandin
What type of fatty acid derivative is important for the myelin sheath on nerve cells? and are the antigenic determinants for the ABO blood groups
sphingolipids
