# Explain how the binding of a transcription factor to an enhancer sequence can increase the rate of transcription of a distant gene.

> IB DP Biology Higher Level (2023 syllabus) — D2.2 Gene expression (HL only) · Explain · 4 marks

## Mark scheme (4 marks)

1. Enhancers are non-coding regulatory DNA sequences that can be located far from the gene they regulate (upstream, downstream, or within an intron).
2. A specific transcription factor (activator protein) binds to the enhancer sequence via its DNA-binding domain.
3. DNA looping brings the enhancer-bound transcription factor into physical proximity with the promoter region / transcription initiation complex.
4. Interaction between the transcription factor and the transcription initiation complex / RNA polymerase II stabilises or recruits the polymerase, increasing the rate of transcription initiation.

## Key terms

- [enhancer](https://www.gradenine.co.uk/glossary/enhancer)
- [transcription factor](https://www.gradenine.co.uk/glossary/transcription-factor)

## Related

- [Revision notes for IB DP Biology Higher Level (2023 syllabus)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-the-binding-of-a-23c54d94) · Published by Druglandscape Ltd.