How is a gene spliced in?
Three steps: (1) Cut gene out of DNA. Specific restriction enzyme used to cut DNA gene out and same restriction enzyme used to cut DNA plasmid. (2) Modify gene if desired. The base sequence may be modified by adding or changing nucleotides. (3) Insert gene into plasmid or genome of other organism. This is done by cutting the plasmid with the same restriction enzyme used in step 1 and then mixing the bacterial plasmids and the genes you wish to insert. In some plasmids the gene will be joined into the plasmid. Bacteria take up these plasmids and are then screened to see which contain the desired gene. Bacteria that contain the desired gene are then cultured and they produce the desired protein, which can be easily harvested. A number of useful human proteins are now produced in this fashion. E.g. Insulin, clotting factors VIII, human growth hormone. Insulin is now produced primarily this way. It used to be produced by rendering down the pancreases of pigs. Pig insulin is not the same as
