Eukaryotes Flashcards
How many RNAp’s are there in eukaryotes?
3: RNApI RNApII and RNApIII
What are the differences and the roles of each RNAp?
Each one has multiple subunits and its own promoter.
I: Ribosomal RNA’s and is found in the nucleolus.
II: mRNA’s found in the nucleoplasm
III: tRNA’s.
How many subunits is RNApII?
10-14
What’s the main difference between RNApII and RNAp (Prokaryotes)
RNApII cannot initiate transcription alone
What is special about the C terminal domain of RNApII
It has a motif that can be Phosphorylated.
Where can we find Eukaryotic promoters?
Upstream of the start site of transcription.
What are the types of RNApII promoters and their roles?
- Basal (Proximal): Closest to start site, Binds Factors & RNApII.
- Distal: Further away, regulates
3.Enhancers: can be upstream/downstream, regulates
How is RNApII transcription initiated?
When the TATA box is present TFIID binds to it through its TBP that is associated with TAFs. TBP binds to the minor groove of DNA and bends it.
When does the CTD get phosphorylated?
CTD gets phosphorylated at the end of initiation to clear the promoter.
What is the purpose of the 5’ cap?
It protects RNA from degredation
What is the process of adding a 5’ cap?
Add GTP and sometimes methylate 2’ of the two last nucleotides.
What is the process of adding the Poly A tail?
a protein complex binds to two different sites, clumps together and the PolyApolymerase cuts the loop and adds adenosine monophosphate.
What are the 3 transcription Inhibitors? Where do they intervene?
- Actinomycin D (Stops elongation)
- Alpha Amanatin:
- Low [] inhibit RNApII
-High [] inhibit RNApIII
Non competitive inhibition of initiation and Elongation. - Rifampicin. RNAp prokaryotes (prevents promoter clearance)
