KA4: communication and signalling: hydrophobic signals and control of transcription

Question 1

what can hydrophobic signalling molecules diffuse directly through?

And what do they bind with?

Answer 1

-the phospholipid bilayers of membranes

-intracellular receptors

Question 2

what are the receptors for hydrophobic signalling molecules classed as?

Answer 2

transcription factors

Question 3

what are transcription factors?

Answer 3

proteins that when bound to DNA can either stimulate or inhibit initiation of transcription

Question 4

give examples of steroid hormones which are hydrophobic signalling molecules

Answer 4

oestrogen and testosterone

Question 5

where do steroid hormones bind to?

Answer 5

specific receptors in the:

-cytosol or
-nucleus

Question 6

where does the hormone-receptor complex (HRC) move to?

where does it bind to?

what does it affect?

Answer 6

-the nucleus

-specific sites on DNA

-gene expression

Question 7

what are the specific DNA sequences that the HRC binds to called?

Answer 7

hormone response elements

Question 8

what does binding to hormone response elements influence?

Answer 8

-the rate of transcription

with each steroid hormone affecting the gene expression of many different genes