Cundiffe 2 RNA pol

Question 1

HoloEnzyme:

Answer 1

Specific start on native DNA, Random start on foreign DNA

- recognizes promoter, initiates transcription

Question 2

Core enzyme:

Answer 2

random starts on native or foreign

-elongates enzyme completes transcription

Question 3

Bacterial RNA Polymerase (RNAP) is made up of

Answer 3

multiple sub units RNAP
Holo enzyme [core +sigma] of bacterial enzyme
σ = extra subunit

Question 4

Sigma factors:

Answer 4

• recognises promoter
  regulate gene expression in bacteria, turn on/off genes to give diff metabolic & make most of environment
• turn off σ factors at different times
• => temperal regulation

Question 5

σ

Answer 5

must come off after connection => new core enzyme to initiate at another promoter.

Question 6

Transcription bubble:

Answer 6

1 DNA opened over 2 helical turns, initially promoter region -> elongation mode, complementary strand.
Nucleotide can retain phosphate
- unwinding = elongatings
- -need topical isomerase for DNA transcription than replication

Question 7

Termination of transcription:

Answer 7

2 Sometimes dependent on rho factor (p), w/o rho => terminates transcription
at 12 nucleotides σ comes off & recycled
NTP = nucleotide tri phosphate

Question 8

Post transcriptional modification ‘RNA processing’:

Answer 8

3 = Primary transcript -> mature RNA

Prokaryote mRNA not processed

rRNA & tRNA => chemical modification/ cleavage/trimming
commonly at both ends. E.g. methylation => ribose
Not all base but a lot have methylation
c-c glycosidic bond

Question 9

C-N N glycosidic bond

Answer 9

Phosphorylate to UTP

-P-ribose-P

Question 10

Pseudo uridine

Answer 10

synth decides which multiple sites on pre-formed nucleotides

Question 11

Trim multiple

Co-transcriped

Answer 11

ribose nuclease to trim out rRNAs 10% in any cell gene are RNA processing -> proteins have post- processing too.

Question 12

Nuclear RNA Polymerases:

Answer 12

Pol I => large rRNA
Pol II => mMRNA
Pol III => tRNA

Question 13

ANTIBIOTICS & TRANSCRIPTION

Rifamycin binds to..

Answer 13

Beta-subunit of bacterial RNA pol

Question 14

Selective toxicity of bacteria works because

Answer 14

not mammalian => different binding sites in RNAP equivalent in Euk. Is not close enough for antibiotic to bind
e.g. alpha amanitin inhibits RNA Pol II
Amaniti phalloides ‘death cap mushroom’ = fatal => liver damage