CIE A Level Biology (9700) 2019-2021

Revision Notes

19.1.1 Recombinant DNA

Recombinant DNA

  • The genetic code is universal, meaning that almost every organism uses the same four nitrogenous bases – A, T, C & G. There are a few exceptions
  • This means that 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)

Exam Tip

It is because of the universal genetic code that recombinant DNA can be formed. All forms of life use the same genetic code, which is the strongest piece of evidence for evolution. Remember, the genetic code is the basis for storing instructions that, alongside environmental influences, dictate the behaviour of cells and as a result, the behaviour of the whole organism.

Author: Catherine

Cate has over 20 years’ experience teaching Biology to IGCSE, IB and A-level students in seven different countries across Asia, Europe, North America and the Middle East. This has given her a fine appreciation of different cultures, places and teaching methods. Cate has a keen interest in producing Biology revision resources that will help students engage with the subject.

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