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Molecular > Lect 5 > Flashcards

Lect 5 Flashcards

1
Q

Prokaryotes transcription is catalysed by..
It is complementary to ..and identical to…except

A

RNA polymerase
Template strand/ anti sense
Coding strand /sense
T and U

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2
Q

Upstream
Downstream

A

3’
5’

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3
Q

Promoter is
Start point
Numbers are positive

A

Where RNAP attaches upstrem
+1
Downstream

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4
Q

RNA synthesis phases

A

Template binding and preinitiation complex

Initiation
Elongation
Termination

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5
Q

Termination seq is

A

AAU
AAA

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6
Q

Prokaryotic DNA dependent RNA polymerase does not need

A

Primer
Proofreading

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7
Q

Core RNAP

A

1w
2a
1b
1b’
Can not recognize promoter

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8
Q

Sigma factor

A

Recognizes specific promoter
Released after initiation

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9
Q

Holoenzyme

A

Core enzyme+ sigma factor

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10
Q

Promoter region in 2…..
First is….
Second is….

A

Consensus seq
-35, 5’ TTGACA 3’»> RNAP binds to it determines transcription freq
-10, 5’ TATAAT 3’&raquo_space; TATA box , pribnow,

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11
Q

TATA box function in prokaryotes

A

Facilitates the dissociation bet 2 DNA strands due to many A– T bonds making an open complex

Allows RNAP to gain access to transcription site

Ensures fidelity

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12
Q

A consensus seq is

A

A seq that has the same func in different places in the genome

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13
Q

Preinitiation

Initiation

A

RNAP holoenzyme and promoter region
Goes to +1 and adds complementary nucleotides by removing pyrophosphate and ester bonds

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14
Q

Elongation
After 10 nucleotides…..is released
How DNA unwinds
….supercoils ahead…behind

A

Sigma factor
By helicase activity of RNAP
+Ve, -ve

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15
Q

Positive supercoils relaxed by while negative

A

Gyrase
Topoisomerase 1

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16
Q

During the RNA formation…..forms that is dissociated due to….

A

DNA-RNA hybrid
DNA rewinding

17
Q

Termination rho dependent
What is rho

Binds to

It is

Also …dissociated from the strand

A

A protein that recognizes the termination seq

c- rich strand near the 3’ end of the nascent strand

ATP dependent RNA DNA helicase activity

RNAP

18
Q

Rho independent termination

A

Specific DNA seq known as termination site
40-50 bp
Inverted repeats, palindrome
AT rich then CG rich

19
Q

The transcription of the termination site causes…..due to….

A

Hairpin loop
Being a palindrome, inverted repeat

20
Q

Why a string of U’s at the end of termination site

A

To facilitate unwinding of DNA due to weak attraction of AU

21
Q

Enzymes and their inhibitors
RNA pol Prokaryotic
Mitochondrial RNAP
Eukaryotic Pol II
Eukaryotic pol III

A

Strongly rifampicin
Weakly by rifampicin

Strongly by a- amanitin
Weakly by a- amanitin

22
Q

Eukaryotes transcription have

A

3 nuclear RNAP and 1 mitochondrial
RNA pol I >45 S RNA (18S, 5.8S,28S)
RNA pol II > mrna, snRNA, miRNA
RNA pol III > tRNA, 5S rRna, 1snRna

23
Q

Promoter regions in eukaryotes

A

CAAT box and GC box, -40 to -200 bp, promoter proximal, determine transcription freq

TATA box, hogness box, -20 ,-30 bp
TATAAA
where transcription starts

24
Q

CAAT box func
CG box func

A

CAAT box binding transcription factor CTP

Seq specific DNA binding proteins SP1

25
Q

Factors of RNAPII

A

A
B
D
E
F
H

26
Q

TFIID

A

Only one that directly binds to DNA due to specific high affinity for DNA promoter.

TBP,TATA binding proteins

14 TBP associated factors
Minor groove

27
Q

TFIIF
TFIIH

A

2nd one to bind and brings RNAPII to promoter site

Activates RNAPII BY PHOSPHORYLATION AND KINASE ACRIVITY

28
Q

TFIIH has…activity and…

A

Kinase, to activate RNAP II
Helicase, to separate the 2 DNA strands

29
Q

All the transcription factors leave RNAPII except..

A

TFIIF
Continues to +1 with RNAP forming RNAPII-TFIIF complex

30
Q

Termination in eukaryotes

A

Very far downstream

Consensus seq AAUAAA

after passing 1000+ nucleotides RNAPII becomes dephosphorylated and inactivated by phosphatase enzyme

31
Q

At the end of mRNA processing

A

RNA endonucleases cleave primary mRNA abt 15 bases from consensus seq

Pol II - TFIIF complex dissociated

Molecular (6 decks)

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