39 Synthesis of TG and Membrane Lipids

Question 1

T/F, adipose tissue can perform phospholipid synthesis?

Answer 1

T for their membranes and organelles, but mostly takes the phosphatidic acid and turn it into a triglyceride

Question 2

what is the purpose of VLDL?

Answer 2

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

Question 3

What are TGs packaged into?

Answer 3

VLDLs, processed into the Golgi and then secreted into the blood

Question 4

what are the destinations for TGs?

Answer 4

adipose tissue for storage and muscle for energy use, remember that TGs are transported in the VLDLs

Question 5

what is the composition of a typical VLDL particle?

Answer 5

TG for triglycerides, C for cholesterol, CE for cholesterol esterase and PL for phospholipid

Question 6

what are resting fat levels?

Answer 6

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

Question 7

what kind of fat is phosphatidic acid?

Answer 7

glycerophospholipid with a glycerol, 2 fatty acids, and a phosphate with no head group

Question 8

what is the purpose of having different glycerophospholipids?

Answer 8

they different interaction sites with protein and other extracellular components; so the phospholipid head groups can be interconverted

Question 9

what cofactors are used for lipid synthesis?

Answer 9

CTPs

Question 10

in the interconversion of PLs, what is SAM?

Answer 10

it is a methyl group donor, a major player in biochemical reactions; something we can make and use

Question 11

what is unique about cardiolipin?

Answer 11

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.

Question 12

T/F, a sphingolipid is a glycerophospholipid?

Answer 12

F

Question 13

what are the two parts that sphingolipid synthesis can be divided into?

Answer 13

the formation of sphingosine then the ceramide

the conversion of ceramide to sphingomyelin and glycolipids

Question 14

what are the precursors to sphingosine?

Answer 14

serine and palmitoyl CoA

Question 15

what can happen after the synthesis of a ceramide?

Answer 15

you can attach a choline in which its head can stick out and interact with proteins and other Extracellular molecules

Question 16

what forms a ceramide?

Answer 16

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

Question 17

where is sphingomyelin found?

Answer 17

cell membranes, especially in the myelin sheath producing space between membranes to facilitate conduction of action potentials

Question 18

what happens when you attach a single sugar to a ceramide, what is formed? what about a polysaccharide? purpose?

Answer 18

cerebroside; ganglioside; Very specific structures and functions: primarily cell surface recognition and binding of specific proteins and factors to cell surface.

Question 19

how many carbons is a sphingosine?

Answer 19

18 carbons

Question 20

what is the purpose of glycoproteins, glycolipids and cholesterol on the extracellular face of the plasma membrane?

Answer 20

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

Question 21

where can you find VLDL?

Answer 21

in the liver in response to liver synthesized fat

Question 22

where can you find chylomicron?

Answer 22

in the intestine in response to dietary fat

Question 23

what happens if you take a fasting blood test and see TGs, is VLDL or chylomicrons?

Answer 23

VLDL, because in a fasting state; dietary fat will be absorbed and sent out into the blood and then processed

Question 24

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?

Answer 24

through Lipolipase enzyme and this takes in the VLDL which is liberated by LPL to FAs and the glycerol not used

Question 25

what protein must be recognized by the LPL enzyme? what happens?

Answer 25

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