Metabolism 4

Question 1

regulation of FAS determined by activity of ___? which is regulated by what three things?

Answer 1

acetyl coA caroxylase aka ACC. allosteric effectors, hormone signals (insulin/glucagon) and enzyme induction

Question 2

insulin vs. glucagon: on FAS (what enzyme)

Answer 2

ACC: insulin activates FAS, glucagon inhibits FAS

Question 3

enzyme induction: effect on FAS?

Answer 3

in liver: reponse to chronic over eating = increased capacity for FAS synthesis

Question 4

lipoproteins: common structure

Answer 4

round spherical particle with cholesterol esters or TAGs in middle, and phospholipid monolayer at surface. also has apopproteins on surface for targeting

Question 5

which lipoprotein has the most CEs? TAGs?

Answer 5

LDL have highest composition of cholesterol. chylomicrons have most triacyglycerols.

Question 6

chylomicrons: made where? transported to where? main function?

Answer 6

made in intestines then go to liver for processing, also other tissues. take TAGs from diet to liver for processing

Question 7

liver makes what lipoprotein? go where? deliver what?

Answer 7

makes VLDLs, go to all other tissues to deliver TAGs

Question 8

lipoprotein lipase

Answer 8

found in blood stream, essential for delivery of TAGs (break down VLDL into TAGs in tissues)

Question 9

VLDL after going to other tissues from liver

Answer 9

turned into LDL, then back into liver or other tissues. or turned into HDL, taken up by liver.

Question 10

cholesterol is made from? where?

Answer 10

acetyl coA; mainly in the liver

Question 11

cholesterol synthesis: pathway involves?

Answer 11

more than 20 different reactions from HMG coA to cholesterol

Question 12

rate limiting enzyme for cholesterol synthesis

Answer 12

HMG co A reductase

Question 13

HMG co A reductase regulated in two major ways?

Answer 13

induction/repression. hormone signals (insulin stimulate, glucagon inhibits cholesterol synthesis)

Question 14

what drug to inhibit cholesterol

Answer 14

statins: inhibit HMG co A reductase

Question 15

good vs. bad cholesterol?

Answer 15

HDL (good) inhibits HMG co A reductase = down regulates cholesterol synthesis. LDL (bad) desensitizes receptors so no longer taken up into cells

Question 16

LDL particles delivered by?

Answer 16

receptor mediated endoytosis

Question 17

removal of excess cholesterol from peripheral tissues done by what?

Answer 17

via HDL and transporter/flippase

Question 18

amino acid break down: what happens to the two components

Answer 18

NH3 toxic. carbon skeleton feeds into catabolism depending on size: into CAC, or converted into acetyl co A

Question 19

glucogenic or ketogenic amino acids

Answer 19

glucogenic = make glucose (like pyruvate of OAA). ketogenic = makes acetyl co A

Question 20

summary of insulin’s actions

Answer 20

fed state; promotes storage: upregulate GLUT so more uptake into cells, activates glycolysis, activates FAS and TAG synthesis and glycogen synthesis

Question 21

summary of glucagon’s actions

Answer 21

fasted state so promotes mobilization of fuel: down regulate GLUT, inhibit glycolysis, activate lipolysis, activate BOX, glycogenolysis and glucogenesis