Lecture 10 RNA Polymerases Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

RNA Polymerases are known as…

A

Macromolecular complexes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How many RNA polymerases are there in prokaryotes

A

1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How many RNA polymerases are there in Eukaryotes

A

3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the three names of Eukaryotic RNA polymerases

and what genes do they transcribe

A

RNA Polymerase I transcribes ribosomal RNA genes
RNA Polmerase II transcribes mRNA and snRNA genes
rNA Polymerase III transcribes tRNA and snRNA genes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe the 6 structural features of the prokaryotic RNA Polymerase

A

1 Sigma subunit
2 Alpha subunits
2 Beta subunits
1 Omega subunits

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the role of the sigma subunit in prokaryotic RNA polymerase

A

promoter recognition.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the function of the 2 alpha subunits in RNA polymerase

A
  • Help to assemble the enzyme

- smaller subunits

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the function of the 2 beta subunits in RNA polymerase

A
  • larger subunits
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the function of the omega subunit in RNA polymerase.

A
  • not universally required for transcription
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Explain the process of transcription initiation complex formation in RNA polymerase II

A
  • Transcription factor TFIID binds,
  • TFIID is a big molecule made up of TBP and TAFs.
  • TBP is only dna specific interaction, locates and binds to the TATA box of the promoter region.
  • TFII A function is to help TFII D binding
  • TFIIB function is to measure the distance from the TATA box to the transcription start site.
  • Formation of the tf DAB complex recruits RNA polymerase
  • RNA polymerase binding is accompanied by several other Transcription factors TFII E,F,H,J,K.
  • TFE,F,J,H,K, have several functions that include processivity (helping RNA polymerase to stay on DNA without wondering off, transcription termination,
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Which is the largest subunit in prokaryotic RNA polymerase

A

beta subunits

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Explain the process of transcription initiation in prokaryotic RNA Polymerase

A

Holoenzyme assembles onto DNA.
Sigma subunit recognizes and binds promoter.
Sigma subunit moves off DNA leaving just the core enzyme

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the function of the TFIIB

A

Transcription factor II B’s function is to measure the distance from the TATA element to the transcription start site.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the function of TFIIA

A

function is to help assist TFIID to bind. It is an accessory molecule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the function of TFIID

A

This is a transcription factor. It is a big molecule made up of TATA binding protein (TBP) and Transcription associated factors. TBP recognizes the TATA element sequence in the promoter and binds to it.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the functions of Transcription factors TFII E,F,J,H,K

A
  • non specific blocking
  • promoter clearance
  • processivity (helps RNA polymerase to stay bound to DNA)
  • helicase activity (breaking base pairs)
  • Other TFs are there for DNA repair.
  • TFs are coupled to DNA and scan DNA for errors and repair any errors.
17
Q

Describe the sequence of events that occurs during transcription initiation with RNA Polymerase I

A
  • Upstream binding factor UBF binds to the UCE and core element, looping the DNA in a loop
    • SL1 is made of TBP and Polymerase I specific Transcription associated factors (TAFs)
    • TAFs - specific for recruiting RNA polymerase I
    • Sl1 doesn’t interact with DNA, instead recruits other proteins
    • RNA polymerase I binds to the complex and transcription is initiated.
    • Transcription binding protein is a common factor between Pol I and Pol II
    • TBP is essential for recruiting polymerase for all three types of gene but only in one case does TBP actually bind specifically to DNA, in Polymerase II.
    • SL1 is similar to TFIID, as they both contain TATA binding protein, but different set of TAF transcription accessory factors.
18
Q

What is SL1

A

SL1 is made up of TBP and polymerase I specific transcription associated factrors.

19
Q

Does SL1 interact with the DNA

A

no

20
Q

What is the role of SL1

A

recruits proteins.

21
Q

Which molecule is SL1 similiar too

A

TFII D as they both contain TATA binding protein, TBP. But they both contain a different set of TAF transcription factors.

22
Q

Which RNA polymerase contains SL1

A

Eukaryotic RNA Polymerase I - which transcribes ribosomal RNA

23
Q

Describe the sequence of events for transcription initiation in Eukaryotic RNA Polymerase III

A
  • RNA Polymerase III promoter sequence is inside the coding region
    • TFIIIC binds to the B box
    • TFIII B is recruited upstream of the start site.
    • TFIII B is made up of TBP + 2x Pol III specific TAFs.
    • Once TFIIIB is recruited, TFIIIC is disposed of.
    • Lastly, RNA polymerase III is recruited and initiates transcription.
24
Q

Which Polymerase is associated with TFIII B

A

Eukaryotic RNA Polymerase III

25
Q

What is TFIIIB made up of

A

TBP and 2x Polymerase III specific TAFs.

26
Q

Describe the sequence of events for transcription initiation for prokaryotic RNA Polymerase

A
  • Must first locate the promoter sequence, orient itself on the promoter region (carried out by sigma subunit)
  • Loses sigma subunit to lose sequence specificity (after it has bound to promoter)
  • Alpha beta and omega subunits remain and transcribe the DNA.
  • Alpha, beta and omega form the CORE enzyme
  • When core enzyme is linked to sigma subunit, it is known as the holoenzyme.
  • Core enzyme carries out transcription elongation
  • Holoenzyme binds to DNA and initiates transcription.
27
Q

What forms the core enzyme

A

Alpha, beta and omega subunits. It is formed after loss of the sigma subunit.

28
Q

What is the holoenzyme

A

When the core enzyme is linked to the sigma subunit.

29
Q

What is the function of the core enzyme in Prokaryotic RNA Polymerase

A

To carry out transcription elongation.

30
Q

What is the function of the holoenzyme in prokaryotic RNA Polymerase

A

Binds to the DNA and initiates transcription.