4. Gene structure

Question 1

What are regulatory factor?

What are the two main types?

Answer 1

Required by RNA polymerase to initiate transcription

1. Cis acting - located within the gene that they regulated
2. Trans acting - produced by remote genes, migrate to the site of action

Question 2

What is a gene promoter?

What are the different regions?

Answer 2

RNA polymerase binds to promoter to initiate transcription

1. Core promoter - contains RNA pol binding site, transcription start site and TATA box (where TFs and histones bind)
2. Proximal promoter elements - approx 250 bp upstream of TSS, primary regulatory elements
3. Distal promoter - further upstream, regulatory elements with weaker influence

Question 3

What is an enhancer element?

Answer 3

Modulates rate of transcription in response to binding of specific TFs

Question 4

What is a silencer element?

Answer 4

Bound by repressors, inhibit activation and reduce rate of transcription

Prevent gene expression during differentiation and progression through cell cycle

Question 5

What is an insulator element?

Answer 5

Protects gene from inappropriate signals.

Blocks action of enhancer, acts as barrier to prevent advance of condensed chromatin

Question 6

What are transcription factors?

Answer 6

Proteins that control rate of transcription by binding to specific DNA sequences