The control of gene expression — AQA A-Level Biology
In summary: The control of gene expression is a key topic in AQA A-Level Biology. Key exam tip: Ensure you can clearly explain how epigenetic changes are heritable without altering the DNA base sequence.
Exam Tips for The control of gene expression
- Ensure you can clearly explain how epigenetic changes are heritable without altering the DNA base sequence.
- When discussing recombinant DNA, always mention the universality of the genetic code as the reason why transferred DNA can be expressed in a recipient organism.
- Be prepared to interpret data from gel electrophoresis or DNA hybridisation experiments.
- Use precise terminology when describing stem cell potency (e.g., totipotent vs pluripotent).
- Practice linking the structure of DNA mutations (e.g., frame shift) to the resulting polypeptide structure.
Common Mistakes
- Confusing the roles of DNA methylation and histone acetylation in gene expression.
- Failing to distinguish between the mechanisms of in vitro (PCR) and in vivo (host cell) DNA amplification.
- Misunderstanding the role of reverse transcriptase in producing cDNA.
- Confusing the function of tumour suppressor genes with oncogenes.
- Incorrectly describing the role of RNAi as acting at the transcriptional level rather than translational.
Marking Points
- Distinction between totipotent, pluripotent, multipotent, and unipotent stem cells.
- Mechanism of transcriptional factors moving from cytoplasm to nucleus.
- Role of oestrogen in initiating transcription.
- Epigenetic mechanisms: increased DNA methylation and decreased histone acetylation.
- RNA interference (RNAi) as a mechanism for inhibiting translation.
- Distinction between benign and malignant tumours.
- Role of tumour suppressor genes and oncogenes in cancer development.
- Impact of increased oestrogen concentrations on breast cancer.
← Back to Biology AQA A-Level Specification · All Biology Topics