Genetic Engineering

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Genetic Engineering

Genetic engineering is the deliberate alteration of a living thing's genetic material to change its characteristics. It is also a general term that describes a range of techniques that allow geneticists to transfer genes from one organism to another. The applications of genetic engineering are vast, and since it is technically possible to produce new gene combinations that could never occur in nature, the implications of this new technology are controversial.

Genetic engineering has actually been practiced under another name for thousands of years. Probably the oldest version of it was conducted under the name of agriculture when farmers deliberately crossed plants with certain desirable characteristics and did not breed those without them. They did the same thing with farm animals and called it selective breeding. For example, animal offspring that showed certain desired characteristics were bred with their like, while those not showing desired characteristics were not allowed to reproduce. It was such a technique that gave us the many different types of dogs we have today. However, selective breeding is a slow, trial-and-error process since it must allow animals the time to grow and mature sexually. By the 1970s, once science had developed ways to isolate individual genes and to reintroduce them into cells, they were able to directly and quickly alter the deoxyribonucleic acid (DNA) of an organism and accomplish overnight what would have taken generations.

RECOMBINANT DNA TECHNOLOGY

Genetic engineering is also called "recombinant DNA technology" because the DNA of existing organisms is actually recombined into new organisms. Genetic engineering is a form of gene manipulation that results in a new arrangement of genes. This is achieved by removing a certain part of DNA and attaching it to another piece of DNA, sometimes from a different organism or even a different species. According to what it was intended to do, this transfer might give its new host a new trait, or it might enable it to produce substances that it never before could. Certain crops have been genetically altered or engineered to withstand the

effects of a herbicide that kills weeds. Other plants have had their ability to resist certain diseases transferred genetically to plants without that natural ability. In medicine, genetic engineers have manipulated bacteria and made them cheap, efficient producers of substances needed by humans.

Most of today's genetic engineering is accomplished by inserting genes into bacteria. This recombining is achieved by a relatively simple process described as "cutting and pasting." First a gene is identified, isolated, and spliced or cut out of its DNA strand. In gene splicing, special proteins called "restriction enzymes" are used as scissors. These enzymes react chemically with a certain part of the DNA and break it off, leaving each piece with what are described as "sticky ends." With the help of another enzyme called ligase, these ends will easily attach to any other piece of DNA, even if it comes from a different organism. It is because of this ability that DNA is so easily transferrable between organisms, even ones as different as humans and bacteria. After the gene-containing DNA has been cut out and spliced to another DNA fragment, a hybrid (having mixed composition) molecule called recombinant DNA is formed and inserted back into the cell. When the cell divides, the number of recombinant DNA molecules also increases.

GENETIC ENGINEERING HAS MANY USES

Today genetic engineering has found many uses in agriculture, industry, and medicine. Plants have been engineered to withstand herbicides that kill weeds, as well as to resist insects and even grow in poor soil. In one of the more amazing experimental uses of genetic engineering, genes from fish that thrive in arctic waters have been spliced into plants in an attempt to make them tolerate freezing temperatures. A genetically altered tomato, the "Flavr Savr," can remain on the vine longer and thus does not have to be picked and shipped while still green. In industry, genetic engineering is creating microorganisms that can more efficiently clean up oil spills by naturally breaking down the oil. This also has potential for neutralizing toxic substances and other waste products.

Genetic engineering has received most of its public notice in the medical field. Already, bacteria have been genetically engineered to produce human insulin in large quantities, enabling diabetes treatment to be easier and less expensive. The same has been done for the production of human hormones. Gene therapy is a form of genetic engineering, which introduces a normal gene to make up for a missing or defective gene. Finally, for those who might pass a genetic disease on to their offspring, genetic counseling is now available that allows people to be more informed before they decide to have children.

The recently acquired ability to alter organisms at the level of their genes is more than just another powerful tool of modern science. If we can insert a normal gene in a human to replace a defective one, who is to say we cannot change or modify an existing trait in order to have one that is more "desirable?" The ability to manipulate human beings genetically is an awesome responsibility that some argue should never be attempted. Others say it should be done only under strict guidelines, while others are simply confused by its far-reaching social and ethical implications. There is always the fear that an accident may occur and an uncontrollable bacteria or some other engineered life form might prove to be environmentally disastrous. However, genetic engineering or recombinant DNA technology has such enormous potential for useful and beneficial applications in so many areas that it can never be simply ignored. Fortunately, ethical and legal committees from many disciplines are in place to oversee this crucial work and to consider its future.