Eukaryotic Transmission

Question 1

What do general transcription factors do?

Answer 1

Interact with DNA at the Core Promoter.

-Form the transcription ‘machine’ in combination with RNA Polymerase

Question 2

What are specific transcription factors?

Answer 2

Interact with DNA at the proximal promoter and enhancer

-may be tissue specific and regulate the level and timing of transcription of individual genes

Question 3

Which promoters in eukaryotic protein coding genes are which type of transcription factor?

Answer 3

Specific:

• Enhancer
• Proximal promoter

General:
-Core promoter

Question 4

What are the different types of transcription factor and why are they called what they are?

Answer 4

TFIIA
TFIIB
TFIID
TFIIE
TFIIF

TF = transcription factor
II = RNA polymerase II associated

They are ordered at the core promoter to allow RNA Pol II to associate known as the STEPWISE ASSEMBLY model

Question 5

What do the general transcription factors assemble?

Answer 5

Assemble a transcription complex at the core promoter

Question 6

How are Eukaryotic mRNA’s described as?

Answer 6

capped and polyadenylated

Question 7

What is the role of the mRNA cap?

Answer 7

• protects the 5’ end of the mRNA from degradation and is important for mRNA stability
• cap interacts with translation factors which recruit ribosomes for protein synthesis
• interacts with the cap binding complex involved in export of mRNA from the nucleus
• may be important in the splicing of introns near the 5’ end of the mRNA

Question 8

What occurs at the 3’ end during the end of transcription?

Answer 8

transcription goes past the position at the end of the mRNA to make a longer RNA - which is then cut

Question 9

What is polyadenylation at the 3’ end?

Answer 9

• The base sequence AAUAAA in the mRNA targets a protein complex
• This complex cuts 11-30 bases past AAUAAA
• The remaining mRNA is polyadenylated which is important in determining mRNA stability and in aiding translation