Transcription Stuff Flashcards
What enzyme performs RNA synthesis?
RNA polymerase
What is the DNA strand that isn’t duplicated called?
The coding strand (non-template strand)
Does RNA polymerase need a primer to begin transcription?
No lol
What’s the protein subunit needed to initiate transcription in prokaryotes?
Sigma (lol)
What is the RNA polymerase holoenzyme?
Core RNA polymerase + sigma
What does sigma do?
Guides RNA polymerase to a promoter sequence on the DNA strand
Why are there different types of sigma proteins?
To guide RNA Polymerase to different promoters
What is the -10 box? Where is it found on the promoter?
10 bases upstream from transcription start and usually consists of the sequence TATAAT (or smthn similar)
What is the -35 box? Where is it on the promoter?
35 bases upstream from the transcription start and consists of sequence TTGACA (or something similar)
What is the significance of -35 and -10?
Sigma binds to them to start transcription
What opens the DNA double helix and threads the template strand through the RNA polymerase active site in prokaryotes?
Sigma protein ofc
What happens to sigma once the initiation phase of transcription is completed?
It dissociates from the RNA polymerase
What happens during the elongation phase?
RNA polymerase moves along the DNA template and makes RNA
What occurs during the termination phase?
The RNA polymerase encounters a termination signal in the DNA which includes forming a hairpin
What are the main differences of transcription in Eukaryotes and Prokaryotes?
3 forms of RNA Polymerase (RNA Poly I, II, and III), more than just sigma, and RNA is modified post transcription
What is contained in the primary RNA transcript?
Exons and introns
How are introns removed from the primary RNA transcript?
Splicing
What carries out splicing?
Small nuclear ribonucleoproteins (ssRNPs) which form a complex called a spliceosome
When does splicing usually begin?
BEFORE transcription is completed
What is a 5’ cap? What does it do?
A 7-methylguanosine covalently attached to the 5’ end, needed for the mRNA to exit the nucleus, stability, and needed to bind to the ribosome
What is a 3’ poly A tail? What does it do?
50-250 A nucleotide added to the 3’ end AFTER transcription, catalyzed by poly A polymerase, important for nuclear export and mRNA stability in the cytosol