Transcription in eukaryotes Flashcards
What are the four reasons transcription in eukaryotes is more complex than prokaryotes? IE what are the differences in transcription in prokaryotes versus eukaryotes?
Eukaryotes have more genes that are spaced further apart
Eukaryotes have three RNA polymerases (RNA 1, RNA2, RNA3)
Transcription takes place in the nucleus
DNA in eukaryotes is packed into chromatin
What are general transcription factors in eukaryotes?
these bind sequences in the promoter
What are promoter elements?
specific sequences in the promoter
What happens after the general transcription factors bind to the different sequences in the promoter?
The RNA polymerase two, binds to the promoter at the +1 site.
What happens to the RNA polymerase as it binds to the +1 site on the promoter?
It causes phosphorylation of the C terminal domain, done by transcription factor TF11H
What is the pre initiation complex?
The complex of RNA polymerase 11 and general transcription factors
Why is the CTD of RNA polymerase 11 phosphorylated?
to facilitate the processing of the 5’ mRNA which is capping of m7G
Where is m7g cap and why is it there and what does it do?
is the addition of a methylated guanine nucleotide on the 5’ end of the mrna which protects the mRNA from decay by exonucleases, it also assists in splicing and and translation
What is the poly a signal?
Is when sequences in the 3’ UTR that signal for rna polymerase to to leave rna pol 2 and then signal for additon of poly a tail bi different enzymes
What is the poly A tail?
Is 50-250 A’s added on the 3’ end of mrna
When does the poly A tail get added?
After transcription ends
What does the poly A tail do?
Protects from 3’ end from decay and aid sin translation
How does splicing produce different mrna that encode for different proteins from the same mRNA?
it can be spliced in diff ways near the junctions of exons and introns
What is the kozaq sequence in mature eukaryotic DNA?
the 5’ UTR, is a landing site for ribosomes
What are the diff parts of mature eukaryotic mRNA?
M7G cap
+1 site
5’ UTR
Start codon
coding region
3’ Utr
poly a signal
poly a tail