The general principle of producing a GMO is to add new genetic material into an organism's genome. This is called genetic engineering and was made possible through the discovery of DNA and the creation of the first recombinant bacteria in 1973; an existing bacterium E. coli expressing an exogenic Salmonella gene. This led to concerns in the scientific community about potential risks from genetic engineering, which were first discussed in depth at the Asilomar Conference in 1975. One of the main recommendations from this meeting was that government oversight of recombinant DNA research should be established until the technology was deemed safe. Herbert Boyer then founded the first company to use recombinant DNA technology, Genentech, and in 1978 the company announced creation of an E. coli strain producing the human protein insulin.
In 1986, field tests of bacteria genetically engineered to protect plants from frost damage (ice-minus bacteria) at a small biotechnology company called Advanced Genetic Sciences of Oakland, California, were repeatedly delayed by opponents of biotechnology. In the same year, a proposed field test of a microbe genetically engineered for a pest resistance protein by Monsanto Company was dropped.
In the late 1980s and early 1990s, guidance on assessing the safety of genetically engineered plants and food emerged from organizations including the FAO and WHO. Small-scale experimental plantings of genetically modified (GM) plants began in Canada and the U.S. in the late 1980s. The first approvals for large-scale, commercial cultivation came in the mid 1990s. Since that time, adoption of GM plants by farmers has increased annually. - History Of GMOs
To make a genetically modified organism, three main components are required: the gene you want to transfer, the organism you want to put it into (target species), and a vector to carry the gene into the target species cells. The steps in making a GMO are relatively straightforward, but can be technically challenging. The gene to be transfered (trans-gene) must be cut out and isolated from the original organism. This is usually done by restriction enzymes, which are like molecular scissors, that recognize specific sequences in the DNA and cut it at those places.
A restriction endonuclease is an enzyme that cuts strands of DNA at a specific point. It scans the DNA for a specific target sequence, and when it finds that target sequence it cleaves the DNA. Target sequences are relatively short. For instance, the common restriction enzyme EcoR1 only has a 6 basepair target sequence. To date, thousands of restriction endonucleases (RE) have been isolated, mostly from bacteria. Bacteria use these enzymes as a defense mechanism because the can recognize and cleave foreign (virus) DNA.
Restriction endonucleases can cut double-stranded DNA in a few different ways. Sometimes it cuts both strands at the same position, which causes blunt ends. Other times it cuts each strand at a different point causing overhangs to occur. An overhang means that one strand is longer than the other, and sometimes people refer to this as having sticky ends. See the diagrams below for examples of blunt and sticky ends.
The trans-gene is then inserted into a vector that is capable of getting inside cells of the target species. To do this a scientist removes the portions of the virus’ genome that cause harm, but leave the genes responsible for getting into the host cells. Then the target gene is inserted into the host cells. Once in the host cell the genes will insert into the host’s genome. After this, every time the genome is replicated and new cells are made the trans-gene will also be found the the DNA of each new cell. - Hudson Alpha Institute Of Biotechnology