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