A transgenic organism refers to plants, animals, or microorganisms created using genetic engineering techniques that allow scientists to isolate, edit, and manipulate genetic material—essentially enabling the transfer of DNA between species.

In other words, a transgenic organism is one that has had DNA from a different species introduced into its genome through genetic engineering.

A genetically modified organism (GMO), on the other hand, is a broader term that encompasses any organism whose DNA has been altered using biotechnology—whether that change involves the introduction of foreign genes or simply the editing of its existing genome.

For instance, a plant whose DNA has been modified to grow faster without adding external genes is still considered a GMO but not necessarily a transgenic organism.

“It’s Not Always About Mixing DNA from One Species with Another”

While some academic definitions distinguish between transgenic organisms, transgenics, and GMOs based on their technical differences, all three terms are commonly accepted in general discourse.

“Genetically modified organisms is an umbrella term that includes many different technologies, and transgenics is just one of them,” explains Ana Wegier, a researcher at the Botanical Garden of the Institute of Biology at UNAM. “It’s not always about mixing DNA from one species with another, but rather about introducing changes that don’t exist in nature—always with a specific human interest in mind, often for agricultural or industrial production.”

All Living Organisms Undergo Genetic Modifications

Strictly speaking, and according to an article published in the journal Gene, humans have been modifying DNA for thousands of years simply by selecting certain plants or animals for breeding. Selecting cows that produce more milk or tomatoes that grow larger has, over generations, led to genetic changes in these organisms.

The same process happens in nature: organisms that are better adapted to their environment are more likely to survive and pass on their genes. In other words, every living organism has undergone genetic modifications over time, whether through natural selection or human intervention.

“However, when we talk about genetically modified organisms (GMOs), we’re specifically referring to those altered through biotechnology,” the article explains. “The term doesn’t differentiate between genetic changes that occur naturally or through selective breeding and those achieved using genetic engineering tools.”

Defining Genetically Modified Organisms

The development of GMOs and transgenic organisms took a major leap forward with the discovery of Agrobacterium tumefaciens, a soil bacterium capable of infecting plant cells and transferring a specific segment of its DNA into the host’s genome. This bacterium, which causes crown gall disease in plants, became a crucial tool for genetic engineering.

To be more precise, in most scientific contexts, the term Genetically Modified by Engineering Organism (GME) is used exclusively for organisms created using advanced genetic manipulation techniques.

GME refers to all plants and animals whose genomes have been edited through targeted deletions, base pair changes, or DNA insertions—as well as transgenic plants and animals produced by the random integration of DNA from a different species.

Insulin: A Biotech Breakthrough in Medicine

One notable example of a GME-derived pharmaceutical is human insulin, explains Paola Angulo, a professor and researcher in the Department of Bioengineering at Tecnológico de Monterrey and a member of the Food Security research initiative.

“Before, we had to sacrifice large numbers of animals to extract insulin, but now we can produce it inside bacteria like E. coli and other systems,” she says.

If a foreign DNA fragment enters a cell and is not broken down, it can integrate into the cell’s genome through a process known as genetic recombination. In 1979, scientists successfully produced human insulin using genetically engineered microorganisms, such as E. coli.

Before this breakthrough, insulin for diabetes treatment was derived from cattle and pigs—an effective but imperfect solution, as it carried risks for some patients. Thanks to biotechnology, insulin can now be produced more efficiently and with fewer complications.

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