What is Genetic Engineering

What is Genetic Engineering? Genetic Engineering is the manipulation of microbes, plants and animals to make products that are useful to people. As such, genetic engineering is not new. It began a long time ago. I would say that genetic engineering, or biotechnology, began with agriculture. Agriculture I define as the harvesting, planting of cultivation of plants for food and fiber. This was the first biotechnology. Estimates are that agriculture probably began about 10000 years ago, in what is now the region near Iraq.

We have evidence that Sumerians living there at the time learned that barley plants growing around their homes made seeds that could be used to make bear and bread. They started growing these seeds near their settlements. They would use some of the seeds to make bear and bread, and then they would grow the rest of the seeds nearby.

In ancient Egypt, the hieroglyphic symbol for food is a picture of bear and bread. You may ask, why bear? Just to have a good time? Answer is no. When people began to live in settled places, they realized by trial and error that water purity was a big issue. As they would be going to the bathroom in the same water they were drinking, people would become sick. Alcoholic beverages kill most of the bad things that are in water. It’s not surprising that they were invented quite early on by humans.

The process of making alcohol from seeds is actually carried by yeast cells that live in the grain or grapes. This process is called fermentation, and it is a form of biotechnology. Modern genetic engineering, however, refers to the use of a technique called recombinant DNA. To illustrate what is genetic engineering and what are its uses I’d like to tell a story:

As Tom drove home from work, he felt his face twitching and had a really bad headache. Tom was one of the several million people who have a stroke each year in the United States. A blood clot was blocking an artery leading from the heart to his brain. This deprived brain cells of oxygen, and irreversible damage to the brain could occur quite quickly. When you think of blood clots, you got to consider that they do go away eventually. “Go away” is not a really good biochemical term. We say that the clot dissolves, but this happens rather slowly. The way this happens is the following: as the wound is healed, a series of cells that is healing the wound make a substance called TPA (Tissue plasminogen activator), which activates the blood clotting system. The clot then dissolves.

The time factor is important biologically speaking. If the clot dissolved the minute it was formed it wouldn’t do much good. The blood would flow out and you’ll lose it all. Slow dissolving of the clot is a good thing, but not for Tom. Tom was having a stroke, and that’s not a situation in which we want a blood clot for a long time. Every minute the blood flow to the brain is blocked is harmful.

Luckily for Tom, he was near a hospital. He drove to the parking lot; the emergency stuff got him and immediately injected a drug right on the surface of the blood clot. The clot dissolved right away, blood flow was restored and there was minimum damage to the brain. Tom was home the next day and he was fine.

The drug that the emergency room stuff had injected was TPA. This drug is also called PLAT in medical terms. This is the protein that initiates the clot-dissolving process. Without using TPA, the clot would have gone away, but his brain would have gotten damage in the meantime. Adding this substance right away to the site of the clot activated the clot-dissolving system right there.

TPA is made in very small amounts and only when it is needed. The bad thing is that if we want to use that as a medication, we’d better get a lot of it. It’s virtually impossible to get enough TPA from the cells of a body to store in the emergency room. This is when genetic engineering enters the scene.

First, DNA was extracted from human cells. The gene coding for TPA was isolated and inserted in hamsters. This allowed to produce TPA in amounts far greater than you could ever extract from blood. The TPA is then purified and sat on the shelves ready for a patient like Tom.

The scenario of using a gene to produce a useful protein, by this genetic engineering technology, has now been played out for dozen of products. This is part of a revolution. The revolution of genetic engineering.