Let’s imagine that researchers wanted to genetically engineer corn to make it resistant to pests. Here’s a simplified overview of what they would do:
1) First, the scientists need to find an organism that contains the trait they would like their corn to have. In our example, they’ve identified a protein in Bt soil bacteria that can kill pests like rootworm but isn’t harmful to mammals. (Farmers have been spraying their fields with Bt for decades, but it can wash away easily.)
2) They then extract the DNA from the soil bacteria. Here’s a list of ways to extract DNA.
3) Now, the scientists don’t want the entire bacterial genome — they just want the specific gene that controls production of the pest-killing Bt protein. So they use a process called gene cloning to isolate and make many copies of the Bt gene.
4) Next, the scientists may want to modify the Bt gene. This is done in a lab machine by tearing the gene apart with enzymes and repairing certain regions. For example, the scientists might want to design the Bt gene so that only the green leaves of corn produce the pest-killing protein.
5) The newly modified “transgene” is now ready to be inserted into corn DNA. There are a variety of ways to do this. One method is to use agrobacterium, a type of bacteria that can naturally transfer the transgene to the nucleus of the plant cells. There’s also the ”gene gun,” which essentially shoots very tiny gold particles coated with copies of the transgene into the plant cells. This process often has to be repeated hundreds of times before the transgene is successfully integrated into the corn’s DNA.
6) If and when the Bt gene has been successfully inserted into the corn cells, and a new plant with the trait is grown from those cells, the genetic engineering is done. The new “transgenic” corn is now handed over to crop breeders so they can breed it with other corn in more traditional ways to select for other desirable traits.