Eukaryote transcription

What is special about eukaryotic transcription

Occurs within nucleus separate from translation

mRNA must leave nucleus for translation

Different forms of RNA polymerase transcribe

different types of genes

Eukaryotic RNA Polymerases

All eukaryotes possess three forms of RNA polymerase (I, II, & III)

RNA Polymerase II

Responsible for transcription of wide range of

genes in eukaryotes

Its activity is dependent on cis-acting DNA

elements and trans-acting transcription factors

Enhancers & Silencers

DNA sequences found upstream, within, or

downstream of a gene

Enhancers

increase transcription levels

silencers

decrease transcription levels

General transcription factors

Required for all RNAPII-mediated transcription

Transcription activators and repressors

Influence efficiency or rate

of RNAPII transcription initiation

Mediator

structural protein that connects & holds everything together

How does termination occur

No specific sequence for termination of transcription in eukaryotes—unlike

bacteria. RNAP II transcribes beyond the 3’ end of the gene until it reaches the Poly-A signal

sequence. Transcript is cleaved at the signal, Poly-A tail is added later. RNAPII is destabilized, causing it to release the DNA and RNA, terminating

transcription

What does RNA Polymerase I transcribe

rRNA

what does RNA Polymerase II transcribe

mRNA

what does RNA Polymerase III transcribe

tRNA

What are the parts of eukaryotic mRNA

5 cap, 5 UTR, coding sequence, 3 UTR, 3 cap

What does UTR stand for

Untranslated Region

What does dicer do

cuts up the double stranded RNA

What does argonaut do

The protein that binds to the pieces of RNA strand. Creates RISC

What is RISC

RNA induced Silencing Complex