History of Genetic Engineering

Instructor: Bridgett Payseur

Bridgett has a PhD in microbiology and immunology and teaches college biology.

Genetic engineering describes human-made changes to DNA. Boyer and Cohen first developed a method of changing bacterial DNA in the 1970s, and the process has taken off since then.

What Is Genetic Engineering?

Human beings have a long history of manipulating nature for our own benefit. Our ancestors first found they were able to selectively breed friendly wolves to protect us and keep us company, and that we could select for wheat plants that grew enough to feed everyone.

Things have changed a bit in the past ten or so millennia. Now, humans can directly alter the DNA of organisms to give them specific traits. Genetic engineering is a term used to describe the purposeful changes to DNA.

Genetic engineering relies on the production of recombinant DNA. Recombinant DNA refers to any piece of DNA that has been changed around. It gets its name because the DNA pieces have been recombined into new sequences. Recombinant DNA can be made from samples from the same species or from different species. If the recombinant DNA contains information from two or more species, it is called transgenic (trans = across).

Creating Recombinant DNA

How was recombinant DNA first produced? How did a single scientist create the process? Well, it wasn't one single scientist, but many people working together. One such collaboration was between Herbert Boyer and Stanley Cohen, two molecular biologists studying different aspects of DNA in the early 1970s.

Before they met, Boyer had been studying restriction enzymes. These are proteins that are able to cut DNA at specific sequences. The restriction enzyme often leaves an overhanging end, which can be used to attach the DNA to another piece with a complementary end. It's a way of making puzzle pieces that can be joined together out of the DNA.

Cohen, on the other hand, was studying plasmids. Plasmids are small pieces of DNA that bacteria can use to transfer information. Cohen and Boyer decided to combine their research areas to try to genetically engineer a living organism.

Boyer's enzymes were used to cut the DNA segment and the plasmid into complementary pieces. The DNA was placed into one of Boyer's plasmids, which was then introduced into some bacteria. The bacteria were able to copy the DNA segment and pass it on to future generations. This was the first time someone was able to add new genetic information to a cell and have that information passed on.

A plasmid is shown in a bacterial cell.
plasmid

Advances in Genetic Engineering

The technique developed by Cohen and Boyer has been used and improved upon extensively since the 1970s. Many advances have developed since then that have allowed for more effective and varied genetic engineering.

The first genetically engineered mouse was produced in 1980, less than ten years after Cohen's and Boyer's experiments. These mice were used initially to study cancer and viruses. Scientists discovered when and how DNA needs to be inserted during embryonic development in order for it to be passed to future generations.

Plants were the next group of organisms to be genetically engineered, with a transgenic tobacco plant produced in 1983. Many plants are now genetically engineered to grow more easily or provide other consumer benefits.

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