1.4b Hydrophobic Signals and Control of Transcription Flashcards
1
Q
How can hydrophobic signalling molecules pass through the membrane?
A
- They can diffuse directly through the phospholipid bilayer of membranes
- and so bind to intracellular receptors
2
Q
What are the receptors for hydrophobic signalling molecules?
A
Transcription factors
3
Q
What are transcription factors?
A
proteins that when bound to DNA can either stimulate or inhibit initiation of transcription
4
Q
Give examples of hydrophobic signalling molecules
A
Steroid hormones:
-oestrogen
-testosterone
5
Q
Where do steroid hormones bind?
A
to specific receptors in the cytosol or the nucleus
6
Q
What does the hormone receptor complex do?
A
- Moves to the nucleus where it binds to specific sites on DNA and affects gene expression
7
Q
What DNA sites does the hormone receptor complex bind to and what effect does this have?
A
- Binds to specific DNA sequences called hormone response elements (HREs)
-Binding at these sites influences the rate of transcription, with each steroid hormone affecting the gene expression of many different genes
