Whether you’re from the United States, Brazil, Canada, China, India, or almost anywhere else in the world- you are probably familiar with the term GMO. The
debate about GMOs has been hotly contested among scientists, food companies, and the public in recent years. But what exactly are GMOs? How are they made?
And how can we tell if the corn or potatoes we are eating for dinner has been genetically modified?
Let’s start with the basics.
stands for genetically modified organism. It is any organism whose genetic material (its DNA) has been altered in some way via genetic engineering.
Technically, humans have been modifying the genetics of organisms for thousands of years through artificial selection. Artificial selection is the breeding
of certain plants or animals in order to produce an appealing trait. For example: most household dogs are the result of artificial selection. They are the
result of breeding wolves that had more docile characteristics.
In 1973, Herbert Boyer and Stanley Cohen developed a technique that would quickly revolutionize GMO technology. They were able to insert a recombinant DNA
molecule that they created into an E. coli bacterium via a plasmid (The procedure will be explained under Genetics). Thus, they were able to transfer a gene
from one organism into another bacterium that lacked that gene. This new gene encoded for antibiotic resistance. This newfound technology opened up a
whole new age of genetic modification.
Herbert Boyer and Stanley Cohen were able to create antibiotic-resistant bacteria through the means of recombinant DNA technology.
The first step in creating recombinant DNA is selecting the DNA that will be inserted into a cloning vector. Cloning vectors serve as the vehicle of DNA transfer and are usually plasmids or
viruses. Plasmids are small circular pieces of DNA. Plasmids and viruses make good cloning vectors because they contain many of the genetic signals needed for replication. Scientists select the gene
of interest by either isolating it from an organism or by artificially synthesizing the DNA from its components.
Once the piece of DNA is chosen and isolated – the DNA is then cut with a restriction enzyme. A restriction enzyme is an enzyme that cuts DNA molecules at
particular places on the DNA. It is very important that the plasmid vector is also cut with the same restriction enzyme, as this allows for the two to fit
together like puzzle pieces. The DNA insert that was cut by the restriction enzyme is then ligated to the vector with DNA ligase (glued together). The
vector is then inserted into the host organism, where the recombinant DNA may be expressed by the organism. How do we know it worked? The DNA insert
contains a selectable marker such as antibiotic resistance or a color change, in order to differentiate the organisms who have taken up the vector, as
opposed to the original organism.
Today, there are many different genetic engineering procedures, but many of them share many of the same concepts as talked about above. This technology has
allowed farmers to create plants that are resistant to disease, more nutritious, and even produce beneficial vaccines. However, the controversy over the
possible health and environmental effects of GMOs is still debated.
Some of the pros and cons of GMOs are listed in the chart below.
Increased production of food
Possible allergic reactions
Reduced need for herbicides and pesticides
Gene transfer: Antibiotic-resistance markers being transferred to harmful bacteria
Decreased detrimental impact on the environment due to above
Gene transfer: Modified genes may escape to other crops in the wild
Possibility to make food more nutritious
Very little testing has been done on GM foods ***
Crops are more resistant to the weather; Lower risk of crop failure
Development of herbicide resistant superweeds can result in even more herbicide use
Although this technology has opened up many new research opportunities, there is no general consensus within the scientific community on whether or not
GMOs are safe. It is impossible to give a general consensus on the safety of GMOs. From our discussion on genetics, it should be clear
that scientists can add just about any gene, in theory, to the organism in question. Hence, each GMO has the potential to be radically different from the
next. Although there are many pros to GMOs such as reducing the need of chemicals, the long term risks and effects of altering the genetics of crops on
both human health and the production of super weeds is not yet fully understood, and again, varies for each GMO. One thing is clear, more testing regarding
human health risks needs to be done before each individual GM food hits the market; however this testing is not yet mandatory.
The main debate is whether genetically modified foods should be labeled. GMOs are labeled in many countries such as Japan, Australia, Brazil, Kenya, United
Kingdom, China, and Russia. There are also over 35 countries that have banned GMOs completely. However, if you live in the United States, where there are
no laws requiring the labeling of GMOs, the only way you can ensure that the food you are eating is not genetically modified, that is, genetically modified
within a laboratory, is buying certified organic products.
Harvard University. (2015). From Corgis to Corn: A Brief Look at the Long History of GMO Technology - Science in the News. Retrieved from
Rensselaer Polytechnic Institute (RPI). (2000). An Introduction to Recombinant DNA. Retrieved from