D2.2.2 (HL)—Regulation of transcription
Transcription is regulated by DNA binding proteins, promoters, enhancers, repressors, chromatin state and chemical signals in living cells and tissues.
- Syllabus
- First assessment 2025
- Objective
- D2.2.2
- Level
- HL
Exam analysis
Chance of appearing6%of analysed past papers
Latest appearanceMay 2025
Most common paperPaper2
Typical marks1–7
Common command terms
- Suggest
- Explain
Scoring notes
- Common mistake
- Treating promoters as translation start sites instead of RNA polymerase binding regions.
Recent exam appearances
May 2025Paper2 ["HL"] · TZ19(c)[ 7 ]D2.2.2 (HL)—Regulation of transcription
November 2022Paper2 ["HL"] · TZ04(d)[ 3 ]D2.2.2 (HL)—Regulation of transcription
May 2022Paper1 ["HL"] · TZ227[ 1 ]D2.2.2 (HL)—Regulation of transcription
May 2021Paper2 ["HL"] · TZ27(c)[ 7 ]D2.2.2 (HL)—Regulation of transcription
May 2017Paper2 ["HL"] · TZ28(c)[ 8 ]D2.2.2 (HL)—Regulation of transcription
Practice this objective
Coverage 2014–2025 · Updated 16 Jul 2026
Transcriptional Regulation Sets mRNA Production
HL onlyTranscription factors regulate transcription by binding specific DNA sequences such as promoters and enhancers.
| Regulatory element | Role |
|---|---|
| Promoter | Region near the gene where RNA polymerase and transcription factors assemble to begin transcription |
| Enhancer | Regulatory sequence that increases transcription when an activator transcription factor binds |
| Repressor-bound sequence | Binding can reduce polymerase recruitment or activity and lower transcription |
Different cell types contain different combinations or activities of transcription factors, so the same genome can produce different amounts of a gene's mRNA.
An activator bound to an enhancer can contact the promoter complex and increase how often RNA polymerase initiates transcription.
A transcription factor recognizes a particular DNA sequence; it does not bind every promoter or enhancer indiscriminately.
Regulation of transcription
HL onlyAssessment in practice
1–7 marksHow it is assessed
This objective is assessed through structured response, multiple choice, commonly using Suggest / Explain.
Command terms
Suggest / Explain
What earns marks
Promoters mark where RNA polymerase can bind to begin transcription, while transcription factors bind specific DNA sequences to activate or repress transcription.
Watch for
Treating promoters as translation start sites instead of RNA polymerase binding regions.
Representative question
Question 1
Explain how gene expression can be regulated during transcription to determine an organism's phenotype.
HL Gene Expression Control
HL only- Transcription factors, promoters, enhancers, activators and repressors control RNA polymerase activity.
- mRNA lifetime limits translation; poly-A shortening and nucleases help remove transcripts.
- DNA methylation and histone modification alter chromatin access without changing base sequence, creating epigenetic patterns during differentiation.
- The genome is all genetic information; the transcriptome and proteome vary with cell type, time and environment.
- Some epigenetic marks persist through cell division or inheritance, although most are reset during gamete formation; genomic imprinting is an exception.
- Hormones regulate eukaryotic transcription through receptors and transcription factors; lac and trp operons illustrate bacterial control.
- Twin studies and environmental exposures help separate genetic, epigenetic and environmental effects on phenotype.
Concept essentials
- Promoters help position RNA polymerase for transcription.
- Transcription factors can activate or repress gene expression.
- Enhancers and silencers alter transcription rate.
- Chromatin structure and epigenetic marks affect access to DNA.