39 Synthesis of TG and Membrane Lipids Flashcards
T/F, adipose tissue can perform phospholipid synthesis?
T for their membranes and organelles, but mostly takes the phosphatidic acid and turn it into a triglyceride
what is the purpose of VLDL?
deliver TGs, keep in mind that the composition of the VLDL is TGs and can give to any receiver that wants it, mostly adipose tissue under an insulin signal
What are TGs packaged into?
VLDLs, processed into the Golgi and then secreted into the blood
what are the destinations for TGs?
adipose tissue for storage and muscle for energy use, remember that TGs are transported in the VLDLs
what is the composition of a typical VLDL particle?
TG for triglycerides, C for cholesterol, CE for cholesterol esterase and PL for phospholipid
what are resting fat levels?
TGs and cholesterol and TGs are sampled, VLDLs are being tested in the blood; so higher than normal TGs means that the liver is producing TGs to fast and they cannot be used properly or destination tissues do not need them because they are overloaded with fat and so when TGs are higher than normal then this measurement can be taken for the VLDLs
what kind of fat is phosphatidic acid?
glycerophospholipid with a glycerol, 2 fatty acids, and a phosphate with no head group
what is the purpose of having different glycerophospholipids?
they different interaction sites with protein and other extracellular components; so the phospholipid head groups can be interconverted
what cofactors are used for lipid synthesis?
CTPs
in the interconversion of PLs, what is SAM?
it is a methyl group donor, a major player in biochemical reactions; something we can make and use
what is unique about cardiolipin?
a component of the inner mitochondrial membrane. Its unique structure is suited for filling the lipid spaces within the tight protein crowding in the membrane.
T/F, a sphingolipid is a glycerophospholipid?
F
what are the two parts that sphingolipid synthesis can be divided into?
the formation of sphingosine then the ceramide
the conversion of ceramide to sphingomyelin and glycolipids
what are the precursors to sphingosine?
serine and palmitoyl CoA
what can happen after the synthesis of a ceramide?
you can attach a choline in which its head can stick out and interact with proteins and other Extracellular molecules
what forms a ceramide?
the amide linage of one fatty acid to the sphingosine and so through further modification by addition of a phosphate group and head group conveys structure and function properties, i.e. - sphingocholine
where is sphingomyelin found?
cell membranes, especially in the myelin sheath producing space between membranes to facilitate conduction of action potentials
what happens when you attach a single sugar to a ceramide, what is formed? what about a polysaccharide? purpose?
cerebroside; ganglioside; Very specific structures and functions: primarily cell surface recognition and binding of specific proteins and factors to cell surface.
how many carbons is a sphingosine?
18 carbons
what is the purpose of glycoproteins, glycolipids and cholesterol on the extracellular face of the plasma membrane?
they group together to form rafts which can be long lived or formed transiently based on cell signaling and this creates a surface for the binding of proteins or protein complexes, i.e. coagulation of platelets over a wound
where can you find VLDL?
in the liver in response to liver synthesized fat
where can you find chylomicron?
in the intestine in response to dietary fat
what happens if you take a fasting blood test and see TGs, is VLDL or chylomicrons?
VLDL, because in a fasting state; dietary fat will be absorbed and sent out into the blood and then processed
so for the storage of TG in adipose tissue, we know we have glycerol-3-phosphate, how are FAs able to come so that TG can be formed?
through Lipolipase enzyme and this takes in the VLDL which is liberated by LPL to FAs and the glycerol not used
what protein must be recognized by the LPL enzyme? what happens?
Apo-CII protein, keep in mind that different cell types have different LPL isoforms and this enzyme anchors the lipoprotein to the endothelial cell membrane and protrudes into lipoprotein to grab and hydrolyze the TG
binding, become trapped, fat sucked out, then the lipoprotein becomes smaller as fat is sucked out, APC C-II are no longer exposed and dissociation occurs
