The DNA of the plasmids is cut open with a specific enzyme. The human insulin gene is inserted into each plasmid. The plasmid acts as a vector - it is used to transfer DNA from one organism to another. Bacterial cells are made to take up the genetically modified plasmids.
A small section is then cut out of the circular plasmid by restriction enzymes, 'molecular scissors'. The gene for human insulin is inserted into the gap in the plasmid. This plasmid is now genetically modified. The genetically modified plasmid is introduced into a new bacteria or yeast cell.
Stages of Genetic Engineering
