Control of Gene Expression

AQA A-level BiologyTopic 12 of 1318 lessons

Revision notes for Control of Gene Expression in AQA Biology (7402). Every lesson in BrainCake comes with R.E.C.I.P.E. recall steps, a quick check and spaced reviews.

1. Totipotent Stem CellsStem cells are undifferentiated cells that can divide continually and develop into other types of cell.
2. Pluripotent, Multipotent and Unipotent Stem CellsAs an embryo develops, its stem cells gradually lose potency.
3. Stem Cells in Mature PlantsPlants keep growing throughout their lives, and in mature plants many cells remain totipotent.
4. Induced Pluripotent Stem CellsInduced pluripotent stem cells (iPS cells) are pluripotent cells made from adult body cells. iPS cells can be produced from adult somatic cells…
5. Stem Cells in Treating DiseaseStem cells can divide and differentiate, so they can be used to replace cells that are damaged or missing.
6. Transcription FactorsEvery cell in an organism contains the same genes, but only some of them are expressed.
7. Oestrogen and the Initiation of TranscriptionOestrogen is a steroid hormone that switches on genes by activating a transcription factor.
8. RNA Interference (siRNA and miRNA)Gene expression can also be controlled after transcription.
9. EpigeneticsEpigenetics involves heritable changes in gene function, without changes to the base sequence of DNA.
10. DNA MethylationDNA methylation is the addition of a methyl group (CH3) to DNA.
11. Histone AcetylationHistones are positively charged proteins.
12. Epigenetics and DiseaseBecause epigenetic tags decide which genes are switched on or off, abnormal epigenetic changes can cause disease.
13. Benign and Malignant TumoursA tumour is a mass of abnormal cells formed by uncontrolled cell division (mitosis).
14. Tumour Suppressor GenesTumour suppressor genes are normal genes that slow down cell division.
15. OncogenesProto-oncogenes are normal genes that stimulate cell division.
16. Abnormal Methylation and CancerTumours can form without any mutation in the base sequence, because abnormal methylation can wrongly switch genes on or off.
17. Oestrogen and Breast CancerOestrogen stimulates the growth and division of breast cells as part of normal development.
18. Epigenetic Treatments for CancerUnlike mutations, epigenetic changes can be reversed.

On the specification

• 3.8.2.1 Most of a cell's DNA is not translated
• 3.8.2.2 Regulation of transcription and translation
• 3.8.2.3 Gene expression and cancer

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