Lecture 4

Question 1

How many RNA polymerases exist in eukaryotes?

Answer 1

3. RNA Poly I/ II and III

Question 2

What is an active enzyme complex called?

Answer 2

Holoenzyme

Question 3

What is the function of RNA Poly I and III?

Answer 3

Ribosomal and tRNA synthesis

Question 4

What is the function of RNA Poly II?

Answer 4

Protein coding genes

Question 5

What are they key steps of the Transcriptional Process?

Answer 5

Initiation: Recruits Polymerase
Pause Release
Elongation

Question 6

What is the assembly of Polymerase called?

Answer 6

Pre-Initiation complex

Question 7

What is a Transcription Factor?

Answer 7

Protein involved in transcriptional initiation or elongation or in their regulation

Question 8

What is a promoter?

Answer 8

Regulatory DNA sequence. Defines transcription start site

Question 9

What is the TATA box?

Answer 9

AT-rich sequence: Recruites TATA binding protein (TBP) and (TBP associated factor) TAF

Question 10

What do TAFs do?

Answer 10

Mediate contacts to other transcription factors

Question 11

What is the assembly of the pre-initiation complex?

Answer 11

Promoter recognition: TFIID recognizes promoter and binds via (TATA binding protein) TBP
Assembly of Transcription factors:
RNA PolyII is recruited to promoter region.
TFIIH helps unwind the DNA
Formation of Pre-initiation complex by all transcription factors and RNA Poly II
Initiation: TFIIH phosphorylates C-terminal RNA Poly II and initiates transcription elongation

Question 12

How many bp are transcribed after the first transcription elongation? And why is that?

Answer 12

Only about 20-30. Pause-release -> second phophorylation at CTD occurs. This is done to keep genes “ready to be transcribed” -> transcription can occure faster if genes are already prepared

Question 13

When does splicing occure?

Answer 13

Co-transcriptionally

Question 14

What is the poly-A signal used for?

Answer 14

Transcription termination

Question 15

What is ATP used for in Transcription?

Answer 15

As hydrolysis target in transcription initiation

Question 16

What is the negative control of transcription regulation at the promoter level?

Answer 16

Activation by absence of repressor, but repressor needs to be constantly present

Question 17

What is the positive control of transcription regulation at the promoter level?

Answer 17

Activation by presence of activator, activator only neden when transcription occurs

Question 18

What are promoter functions and where do they lie?

Answer 18

Next to transcription start site and they are needed for RNA pol II positioning, and can bind repressors (regulation)

Question 19

What does gene control of transcription factors depend on?

Answer 19

Availability of factor
Accesibility of DNA
Activity of factor

Question 20

What are common features of transcription factors?

Answer 20

DNA-binding
binds DNA as dimers
co-operate with other factors
mediate transcription activation

Question 21

How does the glucocorticoid receptor work?

Answer 21

Steroid replaces nucleosome and opens a binding site for Transcription factor to activate transcription (normally blocked by nucleosome)

Question 22

What is a co-activator?

Answer 22

Does not bind DNA itself but mediates transcription by interacting with Transcription factors

Question 23

What is the most ubiquitous co-activator of transcription

Answer 23

Mediator Complex

Question 24

What does the mediator complex do?

Answer 24

Mediator complex receives signals from Transcription factors and transcmits them to RNA poly II

Question 25

Can Transcription be fine tuned?

Answer 25

Yes by several factors working in tandem.

Question 26

What are enhancers?

Answer 26

Regulate transcription far away from promoter

Question 27

How do enhancers act?

Answer 27

Regulate through proximity in space

Question 28

How do enhancers work?

Answer 28

Chromatine remodleing or direct interaction with transcription machinery

Question 29

What is a multi-TF complex on enhancercalled?

Answer 29

Enhancosome

Question 30

What is a super enhancer?

Answer 30

Multiple enhancers acting together high density of TF binding sites increased transcriptional activation sustained transcriptional activation

Question 31

Transcription in 5 steps

Answer 31

1: Transcription factor recruitment and remodeling of Nucleosomes 2:Pol II recruitment and progression to start site 3: signal-pause release, beginning of Transcription

Question 32

What are transcription factories?

Answer 32

local concentrations of Transcription factors, RNA Poly and co-activators etc in the nucelus

Question 33

How does MYC become hyperactive in cancer?

Answer 33

By interchromosomal translocation of enhancers -> leads to enhancer duplication -> increase in transcription