Реферат: Genetic Engineering

Introduction

While plant biotechnology has been used for centuries to enhance plants, microorganisms and animals for food, only recently has it allowed for the transfer of genes from one organism to another. Yet there is now a widespread controversy over the harmful and beneficial effects of genetic engineering to which, at this time, there seems to be no concrete solution. The ideas below are expected to bring in a bit of clearance into the topic. Here I’m going to reveal some facts concerning genetic engineering, specially the technology, its weak and strong points (if any). Probably the information brought is a bit too prejudiced, for I’m certainly not in favor of making jokes with nature, but I really tried to find some good things about GE.

What is genetic engineering?

Genetic engineering is a laboratory technique used by scientists to change the DNA of living organisms.

DNA is the blueprint for the individuality of an organism. The organism relies upon the information stored in its DNA for the management of every biochemical process. The life, growth and unique features of the organism depend on its DNA. The segments of DNA which have been associated with specific features or functions of an organism are called genes.

Molecular biologists have discovered many enzymes which change the structure of DNA in living organisms. Some of these enzymes can cut and join strands of DNA. Using such enzymes, scientists learned to cut specific genes from DNA and to build customized DNA using these genes. They also learned about vectors, strands of DNA such as viruses, which can infect a cell and insert themselves into its DNA.

With this knowledge, scientists started to build vectors which incorporated genes of their choosing and used the new vectors to insert these genes into the DNA of living organisms. Genetic engineers believe they can improve the foods we eat by doing this. For example, tomatoes are sensitive to frost. This shortens their growing season. Fish, on the other hand, survive in very cold water. Scientists identified a particular gene which enables a flounder to resist cold and used the technology of genetic engineering to insert this 'anti-freeze' gene into a tomato. This makes it possible to extend the growing season of the tomato.

At first glance, this might look exciting to some people. Deeper consideration reveals serious dangers.

Techniques

There are 4 types of genetic engineering which consist of recombinant engineering, microinjection, electro and chemical poration, and also bioballistics.

r-DNA technology

The first of the 4, recombinant engineering, is also known as r-DNA technology. This technology relies on biological vectors such as plasmids and viruses to carry foreign genes into cells. The plasmids are small circular pieces of genetic material found in bacteria that can cross species boundaries. These circular pieces can be broken, which results with an addition of a new genetic material to the broken plasmids. The plasmids, now joined with the new genetic material, can move across microbial cell boundaries and place the new genetic material next to the bacterium's own genes. After this takes place, the bacteria will then take up the gene and will begin to produce the protein for which the gene codes. In this technique, the viruses also act as vectors. They are infectious particles that contain genetic material to which a new gene can be added. Viruses carry the new gene into a recipient cell driving the process of infecting that cell. However, the viruses can be disabled so that when it carries a new gene into a cell, it cannot make the cell reproduce or make copies of the virus.

Microinjection

The next type of genetic engineering is referred to as microinjection. This technique does not rely on biological vectors, as does r-DNA. It is somewhat of a simple process. It is the injecting of genetic material containing the new gene into the recipient cell. Where the cell is large enough, injection can be done with a fine-tipped glass needle. The injected genes find the host cell genes and incorporate themselves among them.

Electro and chemical poration

This technique is a direct gene transfer involving creating pores or holes in the cell membrane to allow entry of the new genes. If it is done by bathing cells in solutions of special chemicals, then it is referred to as chemical poration. However, if it goes through subjecting cells to a weak electric current, it is called electroporation.

Bio ballistics

This last technique is a projectile method using metal slivers to deliver the genetic material to the interior of the cell. These small slivers, which must be smaller than the diameter of the target cell, are coated with genetic material. The coated slivers are propelled into the cells using a shotgun. After this has been done, a perforated metal plate stops the shell cartridge but still allows the slivers to pass through and into living cells on the other side. Once inside, the genetic material is transported to the nucleus where it is incorporated among host cells.

The history of GE

The concept was first introduced by an Australian monk named Gregor Mendel in the 19th century. His many experiments cemented a foundation for future scientists and for the founding concepts in the study of genetics.

Throughout Mendel's life, he was a victim of criticism and ridicule by his fellow monks for his "foolish" experiments. It took 35 years until he was recognized for his experiments and known for the selective breeding process. Mendel's discoveries made scientists wonder how information was transferred from parent to offspring and whether the information could be captured and/or manipulated.

James D. Watson and Francis H. C. Crick were curious scientists who later became known as the founding fathers of genetic engineering.

Watson and Crick wanted to determine how genetic blueprints are determined and they also proposed that DNA structures are genetic messengers or that chemical compounds of proteins and amino acids all come together as a way to rule out characteristics and traits. These 2 scientists produced a code of DNA and thus answered the question of how characteristics are determined. They also established that DNA are the building blocks of all organisms.

Selective breeding and genetic engineering

Selective breeding and genetic engineering are "both used for the improvement of human society." However, selective breeding is a much longer and more expensive process than genetic engineering. It takes genetic engineering only one generation of offspring to see and study improvement as opposed to selective breeding where many generations are necessary. Therefore, it costs more to observe many generations.

Selective breeding is known as the natural way to engineer genes while genetic engineering is more advanced, technical, scientific, complex and is inevitable in out future.

What are the dangers?

Many previous technologies have proved to have adverse effects unexpected by their developers. DDT, for example, turned out to accumulate in fish and thin the shells of fish-eating birds like eagles and ospreys. And chlorofluorocarbons turned out to float into the upper atmosphere and destroy ozone, a chemical that shields the earth from dangerous radiation. What harmful effects might turn out to be associated with the use or release of genetically engineered organisms?

This is not an easy question. Being able to answer it depends on understanding complex biological and ecological systems. So far, scientists know of no generic harms associated with genetically engineered organisms. For example, it is not true that all genetically engineered foods are toxic or that all released engineered organisms are likely to proliferate in the environment. But specific engineered organisms may be harmful by virtue of the novel gene combinations they possess. This means that the risks of genetically engineered organisms must be assessed case by case and that these risks can differ greatly from one gene-organism combination to another.

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