How Are GMOs Made?

By Marni Wolfe; Updated April 25, 2017
GMOs are common in agriculture with crops such as corn.

Genetically modified organisms or GMOs are currently used in the fields of agriculture, medicine and environmental science. They are organisms that have had genes from another organism inserted into their genetic makeup or genome in a process called recombinant DNA technology; thus they have been genetically modified. The genes inserted into the GMO convey specific advantages to the organism, and therefore can offer a number of benefits. But they are not without controversy.


Of key importance in recombinant DNA technology is the use of plasmids. Plasmids are small, circular strands of DNA present in bacterial cells that are capable of self-replication. These properties, combined with the fact that they carry only a few genes, make plasmids easy to manipulate, and serve as the route to introducing new genes to other cells, according to Arizona State University’s School of Life Sciences.


Constructing a plasmid that carries the gene you want to introduce into your organism is the first step in making a GMO. Plasmids are isolated and treated with restriction enzymes, which will cut the circular strands of DNA at known points. The new genes are then added to the cut plasmids, along with ligation enzymes, which close the plasmid ends and reform the DNA circle. The genetic sequence for many genes is now known and documented, and genes can be manufactured en masse in a process called the polymerase chain reaction or PCR.

Selection and Transformation

When constructing plasmids, they must also contain a marker gene, something that will enable you to identify and select the cells that have successfully obtained the newly constructed plasmids. Antibiotic resistance genes are common markers, ASU's School of Life Sciences says. Once you have introduced plasmids into the organism you wish to modify by a process called transformation, they are grown in a medium containing an antibiotic. Those cells that do not contain the plasmid will die, allowing you to isolate the cells that contain them.


In agriculture, GMOs are used to strengthen crops by making them more disease and drought resistant, and higher in nutrients and yields. Animals that have been genetically modified may have improved health and increased egg or dairy production, according to Oak Ridge National Laboratory. GMOs are also used in waste management, natural resource conservation and in the manufacture of environmentally friendly pest management products. In medicine, GMOs are used in the production of medications and vaccines. They also hold promise in future disease treatments in the forms of gene therapies.


While use of GMOs offers many benefits, there are also a number of controversies surrounding them. At the forefront is safety; there is concern about introducing new products into the food chain that could produce new allergens and antibiotic resistance into the population. There is also the concern of cross pollination, resulting in modifying crops other than the intended ones. Currently, countries have differing requirements regarding the labeling of GMO foods. There is unease in the ethical and intellectual property realms as well.

About the Author

Marni Wolfe began writing professionally in 2009. She has been published in the scientific journals "Brain Research" and "Endocrine," and in various online publications. Wolfe worked for more than 10 years in the pharmaceutical and nutraceutical industries before leaving to write about health and science. Wolfe holds a Bachelor of Science in genetics from the University of Western Ontario.