Regulation of transcription and translation Flashcards
What are transcriptional factors?
Specific molecules that move from the cytoplasm into the nucleus to switch on a gene and initiate transcription
How do transcriptional factors interact with DNA?
They have a site that binds to a specific base sequence on the DNA in the nucleus
What happens when a transcriptional factor binds to DNA?
It activated the region of DNA, beginning the process of transcription, leading to mRNA production
What happens to the gene when the transcriptional factor ia inactive?
The gene remains switched off as the transcriptional factor cannot bind to DNA and initiate transcription or polypeptide synthesis
What is produced when transcription is activated?
Messenger RNA (mRNA), which carries information to be translated into a polypeptide
How do steroid hormones, like oestrogen affect transcription?
They influence gene expression by activating transcriptional factors, enabling them to bind to DNA and initiate transcription
How do hormones like oestrogen switch on a gene?
By combining with a receptor site on a transcriptional factor, activating its DNA binding site
What happens when oestrogen binds to the receptor site on a transcriptional factor?
The DNA binding site on the transcriptional factor changes shape, becoming active
Why is the shape change in the DNA binding site important?
It ensures the transcriptional factor can interact specifically with the target DNA sequence to start transcription
What is the result of the transcriptional factor’s binding site becoming active?
It allows the transcriptional factor to bind to DNA and initiate transcription
How does oestrogen switch on a gene and start transcription?
1) Oestrogen diffuses through the phospholipid portion of the cell - surface membrane
2) Once inside the cytoplasm of a cell, oestrogen binds with a site on a receptor molecule of the transcriptional factor. The shape of the site and the shape of the oestrogen molecule complements
3) By binding with the site, oestrogen changes the shape of the DNA binding site on the transcriptional factor, which can now bind to DNA (it is activated)
4) The transcriptional factor can now enter the nucleus through a nuclear pore and bind to specific base sequences on DNA
5) The combination of the transcriptional factor with DNA stimulates transcription of the gene that makes up the portion of DNA
Why can oestrogen diffuse easily through the cell surface membrane?
Oestrogen is a lipid - soluble molecule, allowing it to pass through the phospholipid bilayer
What is the effect of oestrogen binding to the transcriptional factor?
It changes the shape of the DNA binding site on the transcriptional factor, activating it
What is the result of the transcriptional factor binding to DNA?
it stimulates transcription. of the gene that makes up the DNA portion
