Metabolism 4 Flashcards
regulation of FAS determined by activity of ___? which is regulated by what three things?
acetyl coA caroxylase aka ACC. allosteric effectors, hormone signals (insulin/glucagon) and enzyme induction
insulin vs. glucagon: on FAS (what enzyme)
ACC: insulin activates FAS, glucagon inhibits FAS
enzyme induction: effect on FAS?
in liver: reponse to chronic over eating = increased capacity for FAS synthesis
lipoproteins: common structure
round spherical particle with cholesterol esters or TAGs in middle, and phospholipid monolayer at surface. also has apopproteins on surface for targeting
which lipoprotein has the most CEs? TAGs?
LDL have highest composition of cholesterol. chylomicrons have most triacyglycerols.
chylomicrons: made where? transported to where? main function?
made in intestines then go to liver for processing, also other tissues. take TAGs from diet to liver for processing
liver makes what lipoprotein? go where? deliver what?
makes VLDLs, go to all other tissues to deliver TAGs
lipoprotein lipase
found in blood stream, essential for delivery of TAGs (break down VLDL into TAGs in tissues)
VLDL after going to other tissues from liver
turned into LDL, then back into liver or other tissues. or turned into HDL, taken up by liver.
cholesterol is made from? where?
acetyl coA; mainly in the liver
cholesterol synthesis: pathway involves?
more than 20 different reactions from HMG coA to cholesterol
rate limiting enzyme for cholesterol synthesis
HMG co A reductase
HMG co A reductase regulated in two major ways?
induction/repression. hormone signals (insulin stimulate, glucagon inhibits cholesterol synthesis)
what drug to inhibit cholesterol
statins: inhibit HMG co A reductase
good vs. bad cholesterol?
HDL (good) inhibits HMG co A reductase = down regulates cholesterol synthesis. LDL (bad) desensitizes receptors so no longer taken up into cells
LDL particles delivered by?
receptor mediated endoytosis
removal of excess cholesterol from peripheral tissues done by what?
via HDL and transporter/flippase
amino acid break down: what happens to the two components
NH3 toxic. carbon skeleton feeds into catabolism depending on size: into CAC, or converted into acetyl co A
glucogenic or ketogenic amino acids
glucogenic = make glucose (like pyruvate of OAA). ketogenic = makes acetyl co A
summary of insulin’s actions
fed state; promotes storage: upregulate GLUT so more uptake into cells, activates glycolysis, activates FAS and TAG synthesis and glycogen synthesis
summary of glucagon’s actions
fasted state so promotes mobilization of fuel: down regulate GLUT, inhibit glycolysis, activate lipolysis, activate BOX, glycogenolysis and glucogenesis
