OCR A Level Biology

Revision Notes

6.3.8 Genetic Engineering

Principles of Genetic Engineering

  • Genetic engineering is a term usually used to refer to the manipulation of the DNA sequences of an organism
  • The key feature of the genetic code that makes this possible is that it is universal, meaning that almost every organism uses the same four nitrogenous bases – A, T, C & G. There are a few exceptions
    • Additionally the same codons code for the same amino acids in all living things (meaning that genetic information is transferable between species)
  • Thus scientists have been able to artificially change an organism’s DNA by combining lengths of nucleotides from different sources (typically the nucleotides are from different species)
  • The altered DNA, with the introduced nucleotides, is called recombinant DNA (rDNA)
  • If an organism contains nucleotide sequences from a different species it is called a transgenic organism
  • Any organism that has introduced genetic material is a genetically modified organism (GMO)
  • The mechanisms of transcription and translation are also universal which means that the transferred DNA can be translated within cells of the genetically modified organism
  • Genetic engineering is being used in the new field of science called synthetic biology
    • This is an area of research that studies the design and construction of different biological pathways, organisms and devices, as well as the redesigning of existing natural biological systems

Recombinant DNA, downloadable AS & A Level Biology revision notes

Illustration of a maize plant that has recombinant DNA (DNA from Bacillus thuringiensis)

Recombinant DNA technology

  • This form of genetic engineering involves the transfer of fragments of DNA from one organism/species into another organism/species
  • The resulting genetically engineered organism will then contain recombinant DNA and will be a genetically modified organism (GMO)

Uses of genetic engineering

  • Some of the key uses of genetic engineering include:
    • Genetic modification of crops to increase crop yield through resistance to drought, disease, pesticides and herbicides; or to provide increased nutritional value (e.g. golden rice)
    • Genetic modification of livestock to give disease and pest resistance and increased productivity
    • Genetic modification of bacteria to produce medicines e.g. insulin. Additionally bacterial can be modified to decompose toxic pollutants or carry out large scale chemical production

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