Steroid Biosynthesis

Question 1

How many IPP molecules does vitamin D contain

Answer 1

6

Question 2

The rate limiting step of steroid hormone synthesis is catalyzed by what enzyme?

Answer 2

Desmolase

Question 3

Desmolase catalyzes the formation of what?

Answer 3

Pregnenolone

Question 4

What enhances/stimulates desmolase activity?

Answer 4

ACTH

Question 5

By itself what can Pregnenolone effect?

Answer 5

NMDA glutamate receptor (memory and learning)

Question 6

For synthesis of other progesterones, Pregnenolone must be converted to what?

Answer 6

Progesterone

Question 7

Enzyme that catalyzes Pregnenolone to progesterone?

Answer 7

17-alpha-hydroxylase

3-beta-hydroxysteroid dehydrogenase

Question 8

What type of steroid hormones affect sodium/water levels in tissues?

Answer 8

Mineralocorticoids

Question 9

What type of steroid hormones have affinity for Mineralocorticoid receptors but are 100 times more concentrated than Mineralocorticoids?

Answer 9

Glucocorticoids

Question 10

What type of steroid hormones are performance enhancing drugs (PEGs)?

Answer 10

Androgens

Question 11

Where is aldosterone made?

Answer 11

Zona Glomerulosa

Question 12

Where is cortisol made?

Answer 12

Zona fasciculata

Question 13

Where are steroid hormone synthesized?

Answer 13

ER of adrenal cortex, ovaries, and testes

Question 14

FSH stimulates estero dial production in ovaries by activating what enzyme?

Answer 14

Aromatase

Question 15

Defect in this leads to salt wasting (hyponatremia) and hypotension due to decreased production of aldosterone, and hypoglycemia due to decreased production of cortisol.

In females, this deficiency causes VIRILISM (development of male secondary chacteristics) due to an increased flow of intermediates into adrenal androgens.

Answer 15

21-hydroxylase

Question 16

Deficiency in this enzyme causes a loss of cortisol as well as sex steroids.

However, the decrease in cortisol is compensated for by increased production of corticosterone

Answer 16

17-alpha-hydroxylase

Question 17

Defect in this enzyme causes hypertension due to accumulation of 11-decoxycorticosterone, which has Mineralocorticoid activity

Answer 17

11-beta-hydroxylase

Question 18

Excessive levels of aldosterone leads to this disorder which causes increase blood volume and hypertension

Answer 18

Conn syndrome

Question 19

Elevated cortisol levels are associated with this disorder and are marked by the accumulation of fat on the face and trunk

Answer 19

Cushing syndrome

Question 20

Cortisol levels can be controlled so that they do not signal to the receptors for Mineralocorticoids by what enzyme that converts it to cortisONE?

Answer 20

11beta-hydroxysteroid dehydrogenase

Question 21

Enzyme for testosterone to dihydrotestosterone

Answer 21

5alpha-reductase

Question 22

What drug inhibits 5alpha - redcuctase and can be used to treat benign prostatic hyperplasia or male pattern baldness

Answer 22

Finasteride

Question 23

What is the active form of vitamin D

Answer 23

Calcitriol

Question 24

What do we get vitamin D3 from in the intestinal cells?

Answer 24

Ergocalciferol (vit D2)

Question 25

Enzyme in Liver that converts cholecalciferol (D3) to 25-hydroxycholecalciferol?

Answer 25

25-hydroxylase

Question 26

Enzyme in KIDNEY for 25-hydroxycholecalciferol to 1,25 dihydroxycholecalciferol (Calcitriol)

Answer 26

1 - alpha-hydroxylase