Lecture 10 RNA Polymerases Flashcards
RNA Polymerases are known as…
Macromolecular complexes
How many RNA polymerases are there in prokaryotes
1
How many RNA polymerases are there in Eukaryotes
3
What are the three names of Eukaryotic RNA polymerases
and what genes do they transcribe
RNA Polymerase I transcribes ribosomal RNA genes
RNA Polmerase II transcribes mRNA and snRNA genes
rNA Polymerase III transcribes tRNA and snRNA genes
Describe the 6 structural features of the prokaryotic RNA Polymerase
1 Sigma subunit
2 Alpha subunits
2 Beta subunits
1 Omega subunits
What is the role of the sigma subunit in prokaryotic RNA polymerase
promoter recognition.
What is the function of the 2 alpha subunits in RNA polymerase
- Help to assemble the enzyme
- smaller subunits
What is the function of the 2 beta subunits in RNA polymerase
- larger subunits
What is the function of the omega subunit in RNA polymerase.
- not universally required for transcription
Explain the process of transcription initiation complex formation in RNA polymerase II
- Transcription factor TFIID binds,
- TFIID is a big molecule made up of TBP and TAFs.
- TBP is only dna specific interaction, locates and binds to the TATA box of the promoter region.
- TFII A function is to help TFII D binding
- TFIIB function is to measure the distance from the TATA box to the transcription start site.
- Formation of the tf DAB complex recruits RNA polymerase
- RNA polymerase binding is accompanied by several other Transcription factors TFII E,F,H,J,K.
- TFE,F,J,H,K, have several functions that include processivity (helping RNA polymerase to stay on DNA without wondering off, transcription termination,
Which is the largest subunit in prokaryotic RNA polymerase
beta subunits
Explain the process of transcription initiation in prokaryotic RNA Polymerase
Holoenzyme assembles onto DNA.
Sigma subunit recognizes and binds promoter.
Sigma subunit moves off DNA leaving just the core enzyme
What is the function of the TFIIB
Transcription factor II B’s function is to measure the distance from the TATA element to the transcription start site.
What is the function of TFIIA
function is to help assist TFIID to bind. It is an accessory molecule
What is the function of TFIID
This is a transcription factor. It is a big molecule made up of TATA binding protein (TBP) and Transcription associated factors. TBP recognizes the TATA element sequence in the promoter and binds to it.