14) Unit 1 - Hydrophobic Signalling Flashcards
True or False:
Hydrophobic signals can pass through the membrane readily because the tails of the phospholipids are hydrophobic
True
Where are the receptors of hydrophobic signal located
Within the nucleus or the cytoplasm
Hydrophobic signals can directly influence the ____________ of genes
Transcription
Name the 2 examples of hydrophobic signals
Thyroxine hormone
Steroid hormone
What is thyroxine and what does it do?
A hydrophobic signal which controls metabolic rate by increasing the transcription of the sodium potassium pump.
Explain how thyroxine controls metabolic through increasing the transcription of the Na/K ATPase
1) When thyroxine is not present its receptor protein is attached to the DNA in the nucleus. This inhibits the transcription of the gene for the Na/K pump.
2) When thyroxine attaches to its receptor, the receptor detaches from the DNA due to conformational changes.
3) This allows transcription of the sodium potassium pump. Increase production results in an increase in metabolic rate
What are the receptor proteins for steroid hormones classified as?
transcription factors
What is a transcription factor and what is their effect
- A transcription factor is a protein which binds to DNA and controls the rate of transcription
- Transcription factors can enhance or inhibit the binding as they bind to gene regulatory sequences of DNA which allows for transcriptions to occur.
Explain how steroid hormones influence transcription
Steroid hormones pass readily through the cell membrane of target cells
They bind to their receptor proteins, which act as transcription factors
The transcription factors is then able to bind to gene regulatory sequences of DNA which allows for transcriptions to occur.
Give 2 examples of steroid hormones
oestrogen and testosterone
