lipid metabolism Flashcards
describe the lipoprotein structure?
Hint: the outside is a monolayer of phospholipid and apolipoprotein membrane that contains…
triglycerides and cholesterol esters within. i.e. hydrophobic lipids
cholesterol plays a role in the synthesis of ??? membranes, steroid hormones, bile acid
plasma membranes
role of lipoproteins: carriers and distributors of hydrophobic or hydrophilic (?) lipids such as cholesteryl esters and TGs around the body
hydrophobic
triglycerides play a role as a major source of ???
energy
short chain Fatty acids can enter directly or indirectly (?) into bloodstream?
directly
most dietary fat and all dietary cholesterol must be transferred into ??? to be absorbed
chylomicrons
dietary fat becomes large TG droplets–> liver releases ??? which emulsify fat droplets into lipid membrane –> pancreatic lipase hydrolyses core TGs and free FAs + monoglycerides from the TGs
bile acids released
free FAs and monoglycerides are absorbed by the GI tract and resynthesised into TGS which are then packaged into ??? and released into lymphatic system
chylomicrons
endogenous pathway of TG absorption: VLDL –> IDL –> LDL & HDL –> ??? and this process (mostly) occurs in the liver
sdLDL
chylomicrons are formed by the dietary ??? from exogenous lipid pathway
dietary TGs
chylomicrons transport TGs and ???
cholesterol
VLDL transports endogenous pathway TGs from ???
liver
IDL transports endogenous pathway TGs and ???
cholesterol
LDL delivers cholesterol to ??? in need
tissues/cells
HDL picks up excess ??? from extra-hepatic cells, returns them to the liver
cholesterol
measuring plasma lipid levels:
1. centrifuge to seperate plasma from leukocytes and erythrocytes
2. lipoproteins found in ??? plasma
3. VLDL, IDL, chylomicrons isolated from plasma via ultracentrifugation
4. fasting blood sample in pathology lab –> plasma TG, TC, LDL-C & HDL-C
watery
TRUE or FALSE: apolipoproteins are cofactors for enzymes involved in lipid metabolism i.e. VLDL –> Lipoprotein lipase enzyme + apoCII
–> IDL +FAs
TRUE
apolipoproteins can act as ??? sites for receptors on cell surfaces
recognition
function of apolipoproteins: solubilise insoluble lipids and aid in ??? transport
plasma
exogenous pathway of lipid metabolism step 1:
chylomicrons synthesised from dietary ??? + ??? in the intestine before being released into bloodstream
TGs and cholesterol
Exogenous pathway of lipid metabolism step 2: once in the bloodstream, the chylomicrons are hydrolysed by ??? which releases FAs
glycoprotein lipase
Exogenous pathway of lipid metabolism step 3: chylomicron fragments are taken up by liver and ??? + TGs form pools within the liver
cholesterol
Endogenous pathway lipid metabolism step 1: once arrived at the liver, TG is resynthesised together with cholesterol into ???
VLDL
Endogenous pathway lipid metabolism step 2: ??? hydrolyses core of VLDL to form IDL in bloodstream, releasing FAs.
lipoprotein lipase
Endogenous pathway lipid metabolism step 3: IDL –> LDL which can be taken up by ??? receptor in liver or transported to extrahepatic tissue that is in need of TG and cholesterol.
LDL-receptor
TRUE or FALSE: you can measure chylomicrons, VLDL and IDL using
commercially available kits
FALSE: you cannot!
HDL is the reverse cholesterol transport as it ??? extra cholesterol from extrahepatic tissue and brings back to liver
picks up extra cholesterol
HMG-CoA Reductase converts 3-hydroxy 3-methyl glutaryl CoA to ??? acid
Mevalonic
TRUE or FALSE: bile salts are made in the liver from cholesterol
TRUE
what is the rate limiting enzyme for cholesterol synthesis?
HMG-CoA Reductase
what is the cofactor for lipoprotein lipase?
Apolipoprotein CII
the role of lipoprotein lipase (LPL) is to hydrolyse TGs in ??? as well as VLDL
chylomicrons
lipoprotein lipase influences lipoprotein levels of all types and thus has an influence on ???
atherogenesis
cholesteryl ester transfer protein transfers ??? from VLDL, IDL AND LDL TO HDL in exchange for Cholesteryl Esters from HDL
TGs
what is the cofactor for Lecithin:Cholesterol Acyltransferase?
APO A-1
what tries to equilibrate the core lipids between the different lipoprotein classes = remodelling of lipoproteins?
cholesteryl ester transfer protein
Lecithin:Cholesterol Acyltransferase is a hepatically formed enzyme tuat esterifies ??? free cholesterol on HDL particles = reverse cholesterol transport
plasma free cholesterol
normal sized LDL has more cholesterol per particle than sdLDL but sdLDL gets into arterial wall, becomes trapped and causes ???
atherosclerosis
