transcription

Question 1

what are the 3 phases of transcription?

Answer 1

initiation, elongation and termination

Question 2

what are RNA polymerases?

Answer 2

they are subunit enzymes
plants- are unique
prokaryotes- a single RNA pol

Question 3

RNA polymerase in bacteria and eukaryotes

Answer 3

bacteria: it is small and 5 subunits and complex is jaw like

EU: RNA pol II transcibes mRNA and sRNA
–> couples transcription

Question 4

promotor region in Bactera

Answer 4

RNA pol synthesizes RNA (holoenzyme) 
3 domains 
2: binds to the -10
3: recogizes the -10
4: recognizes the -35 

pro sigma factors: also help to regulate
anti sigma factors: can bind and inhibt the function

Question 5

promotor region in EU

Answer 5

they all need the TATA box to intiate T

1. TFIID binds to TATA
2. TFIIB comes and BRE binds
3. TFIIA binds
4. TFIIH catazlyes, ATP unwinds

pre initation; RNA pol and trans factors

Question 6

promotor region in EU steps

Answer 6

TFII D- B- A- E-H

Question 7

RNA pol I

Answer 7

transcribes rRNA to promote upstream control

Question 8

RNA pol III

Answer 8

transcribes 5s rRNA and tRNA

Question 9

what is the overview of transcritption?

Answer 9

1. RNA pol bonds to promotor
2. trans start at site
3. RNA transported 5-3

Question 10

what are the three enzymes needed for transcription?

Answer 10

1. nucleosome remodeling enzymes
2. histone chaperones
3. enzymes that modify his tails

Question 11

initation overview

Answer 11

1. RNA makes trans bubble
2. ribonuc phos at promotor
3. RNA pol long enough then it will leave promotor site

Question 12

Elongation overview

Answer 12

1. RNA pol adds nuc and makes transcript long
2. RNA pol unwinds DNA ahead
3. DNA repairs behind
4. in bubble some paired with DNA

Question 13

Termination overview

Answer 13

1. RNA pol meets terminatior

2. polymerase dissocates

Question 14

Intiation closed complex

Answer 14

RNA pol and promotor
opens the trans bubble of 14
poll II opened by THIIH and with ATP

Question 15

ATP not needed for which pol

Answer 15

pol I and III

Question 16

open complex

Answer 16

RNA pol bound to open regions of DNA and makes short RNA’s

1. Temp binds RNA pol @ active site
2. NON template held by lid, zipper and rudder regions

Question 17

RNA pol mechanium

Answer 17

2 mg at active site and activate the 3OH and stablize (-)
bacterial and eu TFIIB in abortic initation
have loop endonucleases which helps it break away from promotor

Question 18

elongation= prossive

Answer 18

1. bubble grows with 12-14 unpaired pairs
2. RNA pol separtes downstream DNA
   there is trans arrest

Question 19

transcriptional pausing

Answer 19

1. elongation backtracks (can reverse)
2. trans cleavage factors (chop RNA enchange endonuc)
   - – they bind within the tunnel region of RNA pol

Question 20

Elongation coupled to processing

Answer 20

1. phos makes RNA processing enxymes and ads to the G cap and 5 end of mRNA
2. Capping- phos of second serine in CDP

Question 21

histone chaperones and trans bubble

Answer 21

his chap are ahead of the RNA pol and the bubble moves along unwinding the duplex

Question 22

what are the two main classes in termination?

Answer 22

Intrinsic and Rho dependant

Question 23

Intrisic

Answer 23

1. makes a hairpin
2. string of 8-10 residues

• pairs with poly U tail in bubble
  the hairpin helps the RNA

Question 24

Rho dependant

Answer 24

NO hairpin or Poly A
hexamerase ATP ase w a ring structure
binds to the C rich area and is open but closes when bound to the DNA

Question 25

termination recogozied by

Answer 25

RNA Pol III

Question 26

termination of RNA pol II

Answer 26

keeps going until a signala and mRNA is cleaved at poly A tails

Question 27

what are the two models for termination?

Answer 27

allosteric- RNA pol II transcribes through Poly A and 3 signals-- with CTD torpedo- after downstream cleavage and Rat1 keeps going