Zaidi: Lipids and Lipoproteins Flashcards
(100 cards)
TG
Triacylglycerols
Major storage form of fatty acids
TG composition
one glycerol group and three fatty acid chains
Dietary TG is processed where
in the intestinal cells
De Novo TG synthesis occurs
in liver hepatocytes and adipocytes
TG Synthesis in Intestinal Cells: sequence
TGs are broken down in the lumen of the intestine into
1) FAs
2) 2-monoacylglycerol
Both are transported across the epithelia. Inside, FAs are converted to
1) Fatty acyl CoA
and 2-monoacylglycerol is converted into
1) Diacylglycerol.
Fatty acyl CoA and diacylglycerol are combined to produce Triacylglycerols (TGs), which are packaged with
apolipoproteins and other lipids to form CHYLOMICRONS
After TGs are reassembled in the intestinal cell, what happens
they are combined with apoproteins and lipids = chylomicrons
In the liver, there are a number of events leading to TG synthesis: what are the “big” initial steps
Glucose is converted into DHAP, which is reduced and combined with an oxidized form of glycerol to form Glycerol-3-P.
G3P is combined with fatty acyl CoA to form a number of intermediates, eventually TG
fatty acyl coA is responsible for
activating fatty acids that have been transported from the lumen into fatty acyl CoA inside the cell
Glucose is converted into G3P by
G3P Dehydrogenase
Hepatocyes
Glycerol is converted into ___ by _____
Glycerol 3P by Glycerol Kinase
Hepatocytes
In the liver, de novo FAs are initially
converted into FA-CoA by FA-CoA Synthase, eventually combined with G3P, and subsequently comverted into TG and repackaged into chylomicrons
TG synthesis in adipocytes: what two processes occur before production of a TG happens?
Glucose is broken down via glucose and transformed into G3P.
FA is broken down into FA-CoA
G3P and FA-Coa are combined to eventually form TG and stored
What enzyme activates FA into FA-CoA?
FA-CoA Synthase
VLDL is produced in the
hepatocyte and released into the blood
Capillary Lipoprotein Lipase
Chylomicrons and LDLP are delivered to the adipocyte.
CLPL break these down into FA’s
found in the adipocyte:
breaks down lipoproteins and VLDL to form glycerol and FAs. these are internalized and used for TG formation
In which cell is glucose converted to glycerol by Glycerol kinase?
Hepatocyte. Does not happen in the adipose cell, which uses glycolysis followed by G3P Dehydrogenase to produce Glycerol-3-P
which enzyme is used by hepatocytes to form glycerol but not in adipocytes?
glycerol kinase
What is the source of glycerol in the hepatocyte
it’s moving around freely because of the breakdown of TG but also because of glycolysis
where is glycerol kinase found?
the liver only
CLPL
made by adipocyte but RELEASED out of the adipocyte
breaks down VLDL and chylomicrons into the FAs, which are then used to form TGs inside the cell
where is the source of glycerol in adipocyte?
glycolysis, but lacks the glycerol kinase
Insulin acts on which enzyme in the adipocyte?
capillary lipoprotein lipase
What does Insulin mobilize in adipocytes?
the breakdown of VLDL and chylomicrons by capillary lipoprotein lipase
TG are broken down where
adipocytes
