25.2 Biochem: Steroid hormones

Question 1

What are steroid hormones derived from? What is this substance’s structure?

Answer 1

Cholesterol (4 rings, 27C, C5=C6)

Question 2

What are the steps in the pathway from cholesterol to cortisol?

Answer 2

Cholesterol–>Pregnenolone–>Progesterone–>Cortsiol

Question 3

What are the mineralcorticoids?

Answer 3

Corticosterone and aldosterone

Question 4

How is cholesterol converted to pregnenolone?

Answer 4

Pruning of 27C to 21C

Question 5

How is pregnenolone converted to progesterone?

Answer 5

Keto/enol tautomerisation, double bond moves to C4=C5

Question 6

How do steroid hormones exert their effects?

Answer 6

Remodelling of chromosomes, transcriptional activation

-DNA acetylation and ATP remodelling

Question 7

What are the two major types of transcription factors?

Answer 7

Non gene specific (RNA Pol II)
Gene specific (Nuclear R' specific, assembly of co-activators/co-suppressors)

Question 8

What are the 2 types of nuclear receptors?

Answer 8

Thyroid hormone receptors

Steroid hormone receptors

Question 9

What is an example of a class 1 nuclear receptor? What is needed?

Answer 9

Steroid hormone R’s (Chaperone complex needed)

Question 10

What is an example of a class 2 nuclear R? Where are they located/bound?

Answer 10

Thyroid hormone R’

Located within nucleus, bound to target gene

Question 11

How do nuclear R’s bind co-activators? (2 functions)

Answer 11

Activation function 1: Binds to coactivators, undergoes phosphorylation

Activation function 2: Contains ligand binding site

Question 12

What are many of the steroid receptor co-activators?

Answer 12

HATs (histone acetyltransferases)

Question 13

How does progesterone affect oocytes?

Answer 13

Non-genomic action