RNA Polymerases

Question 1

General structure of RNA polymerase in e. coli

Answer 1

Core enzyme + Sigma sub unit = holoenzyme

Question 2

core enzyme function + holo enzyme function

Answer 2

core enzyme ensures RNAP binds to DNA

holo enzyme recognises promoter region

Question 3

Where does each enzyme start on

• native DNA
• foreign DNA

Answer 3

foreign DNA both random start
core enzyme random start on native
holo enzyme recognises promoter sequence and starts there

Question 4

Purpose of sigma factors in bacteria?

Answer 4

Regulating gene expression

Question 5

How is transcription terminated?

Answer 5

Either rho-dependently or rho-independently

Question 6

How are tRNA and rRNA processed?

Answer 6

Base modification
Ribose methylation
Pseudouridine (Ψ) formation

Question 7

What is a primary transcript?

Answer 7

Freshly transcribed RNA which is yet to be processed

Question 8

How many types of RNA polymerase enzyme in prokaryotes and eukaryotes?

Answer 8

3 in eukaryotes, 1 in prokaryotes

Question 9

Rifamycin is what?

Answer 9

Antibiotic which binds to the B subunit of bacterial RNA polymerase, inhibiting transcription initiation

Question 10

Functions of the 3 RNA polymerases in eukaryotes?

Answer 10

RNAP I makes large rRNAs
RNAP II makes mRNA
RNAP III makes tRNAs