Basic Transcription Part 4 Flashcards Preview

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Flashcards in Basic Transcription Part 4 Deck (51)
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1

Anti termination by N

- can cause anti termination at both rho-dependent and independent terminators
- binds to hairpin to prevent its formation

2

site to the right of cro allows

-polymerase to ignore terminator and enter the delayed early genes

3

Q utilization site (qut site)

- overlaps late promoter PR'

4

in absence of Q

- RNA polymerase pauses for several seconds at qut site
- then transcribes to the terminator and stops late transcription

5

In presence of Q

- Q recognized paused complex and binds qut site
- Q inhibits hairpin formation
- Q then binds polymerase and causes it to resume transcription and ignore terminator and continue into late genes

6

to progress from immediate early to delayed early genes

- requires anti termination by N

7

to progress from delayed early genes to late genes

- requires anti termination by Q
- at qut site just downstream of Q
- Q is a delayed early gene

8

cI

- encodes lambda repressor protein

9

2 promoters control the cI gene

- PRM
- PRE

10

repressor maintenance

- PRM
- used during lysogeny to provide continual supply of repressor to maintain lysogenic state
- requires the product of its own product for activity - auto regulation

11

why PRM cannot be be used to establish lysogeny

- because no repressor present to activate it
- instead PRE is used

12

PRE

- promoter establishment
- located to the right of PR and cro
- directs transcription leftward through cro and then through cI
- allows cI expression before any repressor is available

13

PRE transcription

- cro usually transcribed rightward from PR

14

leftward transcription from PRE

- produces antisense product of cro
- sense product of cI

15

antisense RNA

- helps establish lysogen by binding to cro mRNA
- cannot be translated

16

promoting lysogeny

- Cro works against lysogeny
- blocking cro promotes lysogeny

17

CII

- promotes transcription from a leftward promoter (anti-Q) within Q

18

cII promotes transcription from a leftward promoter (anti-Q) within Q

- promotes Q antisense RNA - blocks production of Q

19

What is Q required for

- late transcription in lytic phase
- interfering with its synthesis favors lysogeny

20

cII function

- can stimulate polymerase to bind only PRE, P1, and anti-Q
- but not other promoters

21

P1

- promoter for integrase for lysogeny

22

PRE area

- -10 and -35 boxes with no similarities to consensus

23

cII interaction RNA pol

- cII required for transcription for transcription
- RNA pol can't bind alone
- cII can't bind alone
- both proteins can bind and form a stable complex around the promoter

24

how do cII and RNA pol bind

- bind cooperatively to the promoter on opposite sides of the helix

25

cIII

- prevents destruction of cII by proteases in the cell (key stop for deciding between lysis or lysogeny)
- works with cII to establish lysogeny by activating PE and P1

26

lambda repressor binds where to do what

- to both OR and OL
- to turn off further early transcription, interfering with the lytic cycle

27

why is turning off cro important

- stimulate own synthesis (lambda repressor) by activating PRM
- allows pol to bind further transcribing the repressor which inhibits transcription from left and right

28

OR division

- divided into three parts
- OR1, OR2, and OR3
- each can bind repressor

29

OR controls

- leftward transcription of cI
- rightward transcription of cro

30

repressor binds most tightly to

- OR1
- then OR2
- and least tightly to OR3