Cholesterol & Steroids

Question 1

cholesterol synthesis requires

Answer 1

acetyl CoA, NADPH, & ATP

Question 2

rate limiting enzyme for cholesterol synthesis

Answer 2

HMG CoA reductase

Question 3

where does cholesterol synthesis occur

Answer 3

cytoplasm

Question 4

steps of acetyl coA to HMG coA

Answer 4

2 acetyl CoA to acetylacyl CoA via thiolase. acetylacyl CoA to HMG CoA via HMG CoA synthase

Question 5

function of HMG CoA reductase

Answer 5

takes HMG CoA to mevalonate. uses 2 NADPH. irreversible step because it releases CoA

Question 6

inhibitors of HMG CoA reductase

Answer 6

cholesterol, statins, glucagon.

Question 7

activator of HMG CoA reductase

Answer 7

insulin

Question 8

explain sterol independent inactivation of HMG CoA reductase

Answer 8

high levels of AMP activate AMPkinase to phosphorylate HMG CoA reductase and render it inactive.

Question 9

statins are what kind of inhibitors of HMG CoA reductase

Answer 9

competitive

Question 10

low cholesterol promotes the release of which stimulatory protein

Answer 10

SREBP (causes the liver to produce more HMG CoA reductase)

Question 11

degradation of HMG CoAR due to high levels of cholesterol or Mevalonate, is done by

Answer 11

proteosomes tagging with ubiquitin

Question 12

lipoprotein with highest amount of cholesterol

Answer 12

LDL

Question 13

increases the amount of LDL receptors on the cell surface to lower serum LDL

Answer 13

statins

Question 14

converts cholesterol to cholesterol ester for storage

Answer 14

ACAT

Question 15

enzyme needed for double bond formation in the b ring of cholesterol

Answer 15

7-dehydrocholesterol reductase

Question 16

disorder associated with absent 7-dehydrocholesterol reductase

Answer 16

SLOS- causes severe mental retardation

Question 17

some cholesterol is modified by bacteria to form

Answer 17

cholestanol & coprostanol

Question 18

most abundant organic components of bile

Answer 18

PC and bile salts

Question 19

primary bile acids

Answer 19

cholic acid & chenodeoxycholic acid

Question 20

rate limiting enzyme for synthesis of bile acids

Answer 20

7-alpha-hydroxlase (puts OH on carbon 7)

Question 21

7-alpha-hydroxlase is inhibited by

Answer 21

cholic acid

Question 22

amino acids involved in bile salt formation

Answer 22

taurine and glycine

Question 23

four functions of bile

Answer 23

eliminates excess cholesterol in feces, prevents gallstone formation, help with digestion of TAGs and help absorb vitamins

Question 24

rate limiting step for steroid synthesis

Answer 24

conversion of cholesterol to pregnenolone via desmolase (cyp11a, p450)

Question 25

transports cholesterol into mitochondria

Answer 25

StAR

Question 26

how does desmolase modify cholesterol in rate limiting step

Answer 26

shortens hydrocarbon chain and hydroxylates steroid nucleus.

Question 27

what does the rate limiting step of steroid synthesis require

Answer 27

NADPH and O2

Question 28

hormone secreted from zona glomerulosa

Answer 28

aldosterone

Question 29

hormone secreted from zona fasiculata

Answer 29

cortisol

Question 30

hormones secreted from zona reticularis

Answer 30

dihydrotestosterone, estradiol

Question 31

peptide that signals cortisol release

Answer 31

ACTH

Question 32

peptide that signals aldosterone release

Answer 32

Ang II or Ang III

Question 33

peptide that signals estradiol release

Answer 33

FSH

Question 34

peptide that signals progesterone and testosterone release

Answer 34

LH

Question 35

how is cortisol transported in the blood

Answer 35

bound to transcortin and albumin

Question 36

raises bp & fluid volume. increases Na+ reabsorption

Answer 36

aldosterone

Question 37

precursor to testosterone and estradiol

Answer 37

DHEA, and androstenedione

Question 38

patient has buffalo hump, hyperglycemia, abnormal hair growth

Answer 38

cushings (too much cortisol)

Question 39

disorder that is the opposite of cushings

Answer 39

addisons.

Question 40

CAH that presents with patient unable to make glucocorticoids, mineralocorticoids, and androgens

Answer 40

3-beta-hydroxysteroid dehydrogenase deficiency. (Unable to take pregnenolone to progesterone)

Question 41

CAH that presents with patient unable to make glucocorticoids and androgens. patient has normal aldosterone

Answer 41

17-alpha-hydroxylase deficiency. (unable to take progesterone to 17-a-hydroxyprogesterone)

Question 42

CAH that presents with patient unable to make glucocorticoids and mineralocorticoids. patient overproduces androgens

Answer 42

21-alpha-hydroxylase deficiency (unable to take progesterone to 11-deoxycortiocosterone) (unable to take 17-alpha-hydroxyprosterterone to 11-deoxycortisol)

Question 43

CAH that presents with patient unable to make glucocorticoids and mineralocorticoids. patient overproduces androgens. also have increased deoxycorticosterone

Answer 43

11-beta1- hydroxylase deficiency (unable to take 11-deoxycortisol to cortisol) (unable to take 11-deoxycortiocosterone to corticosterone)