Cholesterol

Question 1

cholesterol ( sterol) has hydroxyl group at which carbon?

Answer 1

C-3

Question 2

cholesterol is converted to ___ for storage/tansport in blood

Answer 2

cholesteryl esters

Question 3

rate limiting step in cholesterol biosynthesis?

Answer 3

HGM-CoA reductase

2NADPH used 2 NADP+ out

Question 4

3 regulation for HMG-CoA reductase

Answer 4

1. transcriptional control
2. degradation
3. covalent modification

Question 5

how HGM-Coa reductase is transcriptionally regulated?

Answer 5

high CH level -> SCAP-SREBP-DNA binding domain + cholesterol are stucked in ER membrane
when CH level low -> SCAP-SREBP-DNA binding domain are moved to golgi. Protease comes cleaves and DBD goes into nuclues

Question 6

how HGM-Coa reductase is covalently modificated?

Answer 6

glucagon (increase phosphorylation) -> inactive

insulin (phosphatases) –> activate to make CH

Question 7

first step of cholesterol synthesis

Answer 7

3 acetyl coa -> mevalonate (6C)

Question 8

second step of cholesterol synthesis

Answer 8

mevalonate –> isoprene or isoprenoid

6C - > 5C (lose CO2)

Question 9

3rd step of cholesterol synthesis

Answer 9

6 isoprene -> geranyl(C10) -> farnesyl(C15) -> squalene(C30)

Question 10

4rd step of cholesterol synthesis

Answer 10

cyclize linear suqalene and modify it to make cholesterol

Question 11

Farnesyl - PP and geranyl are used to make ___

Answer 11

dolichol, heme A, ubiquionone, vit D, other sterols

Question 12

some is esterified by ___ and packaged into VLDL and shipped out to cells needing CH

Answer 12

ACAT (Acyl-coa-Cholesterol Acyl Transferase)

Question 13

COOH group of bile salts can be ___ to glycine or taurine

Answer 13

conjugated
(turning into hydrophilic state)
ileum reabsorbs over 95% of bile salts

Question 14

bile salt synthesis : -OH @ 3, 7

Answer 14

chenocholate

Question 15

bile salt synthesis : -OH @ 3,7,12

Answer 15

cholate

Question 16

can you digest/metabolize cholesterol? (degrade into CO2)?

Answer 16

NO

<5% loss of bile salts is critical for getting rid of bilesalts

Question 17

this thought to bind CH/bile salts and remove even more

Answer 17

fiber

Question 18

cholesterol is precursor of five classes of steriod hormones

Answer 18

glucocorticoids
mineralocorticoids
androgens
estrogens
progestins

Question 19

what are the two lipoprotein cholesterol diseases?

Answer 19

gall stone (cholesterol:phospholid > 1:1)
atherosclerosis ( ingestion oxidized LDL -> foam cell)

Question 20

two drugs that are used for lipoprotein/cholesterol disease

Answer 20

cholestyramine (lower plasma cholesterol level)

ezetimibe (selectively inhibit reabsorption of CH “specific”)(

Question 21

drug to inhibit HGM-CoA reductase

Answer 21

Statins

lovastatin(lactone) blockes reductase

Question 22

disease due to deficiency of mevalonate kinase

Answer 22

mevalonic aciduria
hyperimmunoglobulinemia D
periodic fever syndrome