lipid metabolism Flashcards
what is the starting product for fatty acid synthesis?
citrate (accumulates in the fed state)
where is fatty acid synthesis occurring?
cytoplasm
how does citrate move into the cytoplasm?
citrate shuttle
how is citrate converted to acetyl-CoA?
ATP citrate lyase
how is acetyl coA converted to malonyl CoA? required cofactor?
acetyl-CoA carboxylase (RLS), biotin
only ___ fatty acids can be made from malignly coA
even chain
where does fatty acid catabolism occur?
in the mitochondria
how are fatty acids transported into mitochondria?
1) fatty acid coA synthetase converts to acyl-CoA
2) acyl-CoA enters mitochondria via carnitine shuttle
what inhibits the carnitine shuttle?
malonyl-CoA (preventing degradation of newly synthesized FAs)
what are the 2 possible fates of B-oxidation products?
ketone bodies
TCA cycle
what is the effect carnitine deficiency?
decreased carnitine shuttle leads to inability to move LCFA into mitochondria
symptoms of carnitine deficiency (3)
weakness
hypotonia
hypokeotoic hypoglycemia
2 substances synthesized from HMG-CoA
cholesterol ketone bodies (acetoacetate)
what is the only energy source of RBCs?
glucose
cannot use ketone bodies (lack mitochondria)
ketone bodies can be used for energy because they are converted to
2 acetyl-CoA
what is the rate limiting enzyme in ketone body synthesis?
HMG CoA synthase
which ketone body is preferred by the brain?
b-hydroxybutarate
what gives breath a fruity odor?
acetone
where are ketone bodies produced?
made in the liver, although the liver lacks the enzymes needed to use them
reaction by HMG-CoA reductase
HMG-COA to mevalonate
function of LCAT
esterifies cholesterol, which allows it to be stored in vesicles (important for transport throughout the body), like HDL
pancreatic lipase
degrades dietary triglycerides to 2 free FA and monoacylglycerol- allows for absorption into enterocyte
lipoprotein lipase location, function
endothelium
degrades triglycerides circulating in chylomicrons, VLDL
hepatic lipase location, function
liver
degrades triglycerides in IDL to form LDL
