Recombinant DNA (Cambridge (CIE) A Level Biology): Revision Note

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 organisms (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)

Principles of Recombinant DNA Diagram

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

• The bacterium species Bacillus thuringiensis contains a gene that codes for a toxic compound (called Bt toxin) that can kill crop pests

• The maize plant does not contain this gene naturally

• The bacterial gene can be recombined into the genome of the maize

• This creates a variety of maize plants that can produce the toxin itself

• This gives the transgenic maize pest resistance, which is of great value in agriculture