Genetic Engineering — страница 2

  • Просмотров 1746
  • Скачиваний 83
  • Размер файла 26
    Кб

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. So far, scientists have identified a number of ways in which genetically engineered organisms could potentially adversely impact both human health and the environment. Once the potential harms are identified, the question becomes how likely are they to occur. The answer to this question falls into the arena of risk assessment. In addition to posing risks of harm that we can envision and attempt to assess, genetic