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Unless you've been living under a rock, you've probably heard about genetically modified, or GM, foods. GM foods are foods that have had their genes messed with in one way or another to benefits us.
Believe it or not, humans have been genetically modifying crops for thousands of years through selective breeding. Selective breeding is what farmers do when they take individual crops that produce more food, resist pests, or simply look prettier, and cross them with other individuals with the same desirable traits. The end result: offspring that have finely tuned genes. Pretty much all the fruits and grains we eat today are the result of selective breeding.
New advances in science have allowed us to take gene modification to a whole new level. Desirable traits in nature don't have to be limited to the species they originate from anymore. We can take desirable traits from one species and insert them into whatever species we like: bacterial genes into animals, fungal genes into plants, you name it. The combinations of gene transfers are endless.
To create a GM food, scientists first have to find the genes responsible for the desirable trait. Say we have a tomato farm that's being overrun with insects. Rather than spraying pesticides until the ground is a toxic wasteland, scientists will find a gene in nature that can do the job. A bacteria that produces proteins that are toxic to insects will do the trick. So how do we get those genes into our tomatoes?
First, we find that gene, cut it out, and insert it into a cloning vector. The vector will also contain genes for antibiotic resistance. Here's why. That vector, also called a plasmid, will be put into host bacteria. Once the bacteria have sucked up the plasmid and are happily replicating, scientists will culture them on a media that contains an antibiotic. Those without the plasmid will die, and those with the antibiotic resistance carrying the wanted genes will survive.
The bacteria act just like copy machines, making more and more cells and more and more plasmids. The plasmids are then harvested from the cells. That's when things get awesome. Scientists smear the plasmids onto gold particles, and then stuff them into a bullet and shoot them into a plant. Seriously, check this gene gun out.
Gene guns fire the gold plasmid particles at plant cells, forcing them into the cell. Once the genes have been blasted into the cell, use those cells to produce a seedling, and voila: insect resistant tomatoes, no pesticide needed.
Here are some other common GM foods.
While there are lots of examples of GM crops, GM livestock animals are far less common. As of 2015 in the US, only GM salmon have been approved for human consumption. These salmon have had genes added from other fish species that allow the salmon to grow larger, faster. Some animals have been modified to produce proteins for pharmaceuticals in their milk: camels, goats, sheep, cows, even hamsters. We don't even want to know how to milk a hamster.
GM foods are wrought with controversy. Everyone's got an opinion on the matter. Everyone, that is, except us here at Shmoop. We're staying out of it.