3 - Gene organisation and transcription I

Question 1

What is the antisense strand?

Answer 1

the DNA strand that gets transcribed

it is ‘antisense’ because it is opposite of the RNA that is produced

Question 2

Which enzyme carries out transcription?

Answer 2

RNA polymerase

Question 3

What is the gene promoter?

What is the sequence that signifies to RNA polymerase II?

Answer 3

the DNA sequence at which RNA polymerase binds

TATA

Question 4

What is a transcription factor?

Answer 4

DNA binding proteins that regulate the amount of transcription of a gene

Question 5

What are the names of the TFs that activate and suppress gene expression respectively?

Answer 5

Activators and Repressors

Question 6

What is the purpose of the basal transcription complex?

Answer 6

allows RNA Pol II to be phosphorylated so it engage in transcription

Question 7

Give the order of the components of the BTC assembly

Answer 7

• TF IID
• TF IIA and TF IIB
• RNA polymerase binds to TF IIB with TF IIF bound to it
• TF IIE, TF IIH and TF IIJ bind to RNA polymerase

Question 8

What does TF IID consist of and what happens when it binds to TATA?

Answer 8

consists of TATA binding protein (TBP) and TBP Accessory Factors (TAFs)

when it binds, it widens the groove (so allows extensive contact with bases)
NOTE: unwinding is symmetrical, so transcription is unidirectional

Question 9

What is the importance of TF IIB?

Answer 9

it can bind to TF IID and RNA Pol II

Question 10

How do transcription factors work?

Answer 10

• remodel chromatin (they bind onto TF binding sites and bend the DNA)
• recruitment of enzymes that modify histones though acetylation
  hyperacetylation = gene expression
  hypoacetylation = gene repression