Transcriptional Factors + Regulating Translation Flashcards
What do transcriptional factors do, generally?
They inhibit or stimulate the trasncription of target genes.
How do transcriptional factors inhibit/stimulate the transcription of target genes?
When they move from the cytoplasm to the nucleus
What enables cells to become specialised?
When certain genes are turned on/off in a cell
What type of biological molecule are transcriptional factors?
3D Protein
How do transcriptional factors initiate transcription?
They bind to specific DNA base sequences (bind to the DNA once they have entered the nucleus from the cytoplasm) which enables RNA polymerase to bind and therefore transcription can start.
Transcription factors bind to two different molecules, what are they?
DNA and steroid hormones. There is a DNA binding site and the other part acts as a receptor for another molecule to bind to before it can bind to the DNA e.g steroid hormones such as oestrogen
Once the transcriptional factors have bounded to the DNA, what happens?
Allows RNA polymerase to bind, creating an mRNA molecule for that gene which can be later translated in the cytoplasm to create the protein
What would happen without the binding of the transcription factor?
The gene is inactive and the protein won’t be made
Give one example of a molecule that activates a transcriptional factor?
Oestrogen
What is oestrogen?
A steroid hormone, which is lipid-soluble and initiates transcription
How does oestrogen enter cells and why?
Simply diffuses through the phospholipid bilayer that makes up a cell membrane because it is lipid-soluble
What does oestrogen do once it enters cells?
It binds to the receptor part of a transcriptional factor because it has a complementary to the receptor
Once oestrogen has binded to the transcriptional factor, what happens?
The shape of the DNA binding site (of the transcriptional factor) changes which makes it complementary in shape to the DNA so that it is able to bind to it. Then the activated TF moves through nuclear pores into nucleus and is able to bind to DNA, so RNA polymerase can attach and mRNA is created.
What is an activated transcriptional factor?
A transcriptional factor that has a DNA binding site that is complementary to the DNA (sometimes a molecule is needed to stimulate that DNA binding site to change shape)
When can RNA polymerase attach to DNA to create an mRNA strand? And why?
Once the TF has attached because RNA polymerase is a protein so has a specific 3D tertiary structure and the active site of RNA polymerase is only complementary in shape to the TF and DNA together. So they have to be bound for transcription to occur.
