GMO stands for Genetically Modified Organism. Let’s break it down word by word. Genetically refers to genes. Genes are made up of DNA, which is a set of instructions for how cells grow and develop. Second is Modified. This implies that some change or tweak has been made. Lastly, we have the word Organism. When it comes to GMOs, many people only think of crops. Yet an ‘organism’ isn’t just a plant; it refers to all living things, including bacteria and fungi.
With that in mind, GMOs are living beings that have had their genetic code changed in some way. While conventional breeding, which has been going on for centuries, involves mixing all of the genes from two different sources, producing a GMO is much more targeted. Rather than crossing two plants out in the field, they insert a gene or two into individual cells in a lab. Yet, as mentioned earlier, GM technology can also be used on microorganisms. For example, bacteria have been genetically modified to produce medicines that can cure diseases or vaccines that prevent them. A commonly used medicine that comes from a genetically modified source is insulin, which is used to treat diabetes, but there are many others.
The process to create a GMO starts very small. A scientist causes a gene to be inserted into the DNA in the nucleus of a single cell. The DNA being used for the modification is so small that it can’t be seen, even under the most powerful microscope. Despite how tiny a cell is, there is a massive amount of DNA all packaged into its one little nucleus. To give some idea of just how much DNA is packed into that small space, if you were to take all the DNA of one single corn cell out of the nucleus and line it up end-to-end, it would be about six feet long! Into this enormous amount of DNA, a very small piece is inserted. A vast majority of the organism’s genetic code remains completely unchanged by the process.
Once this single cell has been modified, the scientist will treat it with naturally occurring plant hormones to stimulate growth and development. This one cell will start to divide (which is the natural growth process for any organism) and the resulting cells begin to take on specialized functions, until they become a whole plant. Because this new plant was ultimately derived from a single cell with the inserted gene, all of the cells in the regenerated plant contain that new gene.
From: Purdue Science of GMOs