BRAINCAKETranscription Factors
Transcription factors are proteins that control whether a gene is transcribed. They move from the cytoplasm into the nucleus and bind to specific base sequences in the DNA, usually in or near the promoter of a gene.
• Activators help RNA polymerase to bind to the promoter, so transcription starts or increases.
• Repressors bind to the DNA and block RNA polymerase, so transcription is prevented or reduced.
Each transcription factor has a DNA-binding site with a shape that fits a particular base sequence, so it only affects genes with that sequence. One transcription factor may control many genes, and one gene may be controlled by several transcription factors. Transcription factors are themselves coded for by genes, so switching on one transcription factor gene can switch on a whole set of other genes.
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More in Gene Expression
- Gene Expression
- Gene Probes
- Control of Gene Expression
- RNA Splicing
- Epigenetics
- DNA Methylation
- DNA Demethylation
- Euchromatin and Heterochromatin
All 39 lessons in Gene Expression · All Edexcel A-level Biology topics