RNA polymerases - Lecture 9

Question 1

How many polymerases do prokaryotes have?

Answer 1

One RNA polymerase

Question 2

How many polymerases do eukaryotic cells have?

Answer 2

Three

Question 3

What are the three types of RNA polymerases in eukaryotes?

Answer 3

Polymerase I
Polymerase II
Polymerase III

Question 4

What is polymerase I involved in?

Answer 4

Ribosomal RNA genes (rRNA)

Question 5

What is RNA polymerase II involved in?

Answer 5

Protein coding genes (mRNA)
Small nuclear RNA (snRNA)

Question 6

What types of eukaryotic RNA is RNA polymerase III used for?

Answer 6

Transfer RNA (tRNA),
rRNA and
snRNA

Question 7

What is prokaryotic RNA polymerase made up of?

Answer 7

RNA polymerase holoenzyme
Sigma sub unit
2x alpha subunit
2x beta subunit
omega subunit

Question 8

What does the sigma subunit do in prokaryotic RNA polymerase?

Answer 8

Recognises the promoter
It dissociates when the promoter is recognised and attached

Question 9

What do the alpha subunits do in prokaryotic RNA polymerase?

Answer 9

Involved in assembly and activation

Question 10

What do the beta subunits do in prokaryotic RNA polymerase?

Answer 10

Involved in catalysts and terminationW

Question 11

What does the omega subunit do in prokaryotic RNA polymerase?

Answer 11

Involved in assembly and folding
Is required for some genes

Question 12

What features do genes that make different RNA types have?

Answer 12

Different architecture
Use different RNA polymerases

Question 13

What is the TFIID made up of?

Answer 13

Its a multi protein complex
Made up of TATA binding protein (TBP)
and TBP associated factors (TAFs)

Question 14

What is the first stage of the assembly of the RNA polymerase II initiation complex?

Answer 14

TFIIA helps TFIID to bind
TFIIB sets the distance from TATA element to start site

Question 15

What is the TBP DNA complex?

Answer 15

From the underside of the beta sheet surface the TBP has contact with the DNA minor groove

Question 15

How does RNA polymerase I bind?

Answer 15

Upstream binding factor binds to UCE and core element in DNA
This attracts SL1 (which is made up of TBP and polymerase I-specific TAFs(protein complex))
RNA polymerase I binds to complex and transcription and initiated

Question 15

What is part II of the RNA polymerase II initiation complex?

Answer 15

There’s interaction with the D-A-B complex and recruitment of polymerase II
This blocks the non-specific binding of polymerase II to DNA
Promoter clearance
Helicase
Processivity, elongation
Transcription-coupled DNA repair

Question 15

How does RNA polymerase III bind?

Answer 15

The promoter is within a coding region
TFIIIC binds to the B box
TFIIIB recruited upstream of the start site
TFIIIB = TBP and 2 polymerase III specific TAFs
Once TFIIIB is recruited TFIIIC is dispensable
RNA polymerase III recruited and initiates transcription