AQA A Level Biology

Revision Notes

8.2.6 Evaluating Data about Genetic Expression

Interpret & Evaluate Data about Genetic Expression

RNA analysis

  • RNA analysis is important with regards to gene expression
  • From the outside, most cells look almost identical with the same DNA in their nucleus however they are most likely expressing different genes
  • When a cell expresses a gene, RNA is produced by transcription
  • The RNA present in a cell can be analysed and scientists can match the RNA present in a cell to specific genes and work out which genes are being expressed in that specific cell
  • RNA analysis can be used to find the function of a cell and to determine the differences between cells in a healthy person and a patient with a specific illness
    • For example, the genes responsible for tumour formation can be detected by analysing which genes have been over-expressed within a cancer cell
    • This can lead to the discovery of drugs that block the expression of these genes

Analysing an unknown pathway

  • Gene expression by transcription factors are controlled by signalling pathways
  • Within signalling pathways, proteins bind to each other causing conformational changes (changes in the 3D structure of the protein)
    • This activates the protein and enables it to move on to bind to the next protein in the pathway
  • ATP can be used to phosphorylate, and therefore activate, a protein in a signalling pathway

Exam Tip

When answering questions on gene expression, clarify what is acting on the gene and whether it is having a stimulating or inhibiting effect. Then make sure you understand the effect this will have on the amount of mRNA produced (more expression means more mRNA which means more protein) and what effect this will have on the cell/body.

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