A genetically modified organism is one that includes genes from another organism. Genetic modification is typically done to improve an organism or to produce medicine or food.
Modern genetic modification is an extension of selective breeding, in which organisms with favorable traits are bred and those with unfavorable traits do not. Modern genetic modification allows for a much quicker combination of traits than does selective breeding, which often requires many organisms over many generations. Selective breeding is also far less regulated than genetic modification. In selective breeding, there is no way to control what other genes are combined or amplified. Genetic engineering, however, allows for the transfer of a single desirable trait.
One common use of genetic modification is the creation of crops that are resistant to pests or pesticides. Genetic engineering can also heighten the nutrient content of some plants. Another important use of genetic engineering is the production of insulin. Insulin is harvested from pig intestines and transferred to bacteria. As the bacteria grow, the insulin is collected and purified for medicine.
There are various methods of transferring genetic material from one organism to another. A common method is using bacteria or viruses to carry the genes. Gene guns, small syringes and electric pulses are other tools for genetic modification.