A-LEVEL BIOLOGY AQA NOTES
regulation of transcription and translation
Transcription Factors
- In eukaryotes, transcription of target genes can be regulated by DNA-binding proteins (transcription factors). They can be help RNA polymerase bind (activators) or prevent it binding (repressors),
- The steroid hormone oestrogen, released from the ovaries in women, can initiate transcription in target cells
Regulating Translation
- In eukaryotes and prokaryotes, the translation of mRNA can be inhibited by RNA interference (RNAi)
- RNAi involves the degradation of the mRNA, reducing the gene’s level of expression. Small interfering RNA (siRNA) can carry out this process
Epigenetics
- Epigenetics- changes in DNA that alter the expression of genes without changing the base sequence of DNA itself. It involves the addition of chemical tags onto DNA or histones.
- The epigenetic changes can regulate transcription by changing how tightly the chromatin is packed (chromatin remodelling), affecting RNA polymerase accessibility.
