An Essay on Genetic Engineering
In 1973, the discovery of DNA and the creation of the first recombinant bacteria, allowed the genetic principle of producing a Genetically Modified Organism, otherwise known as GMO to evolve. This is where genetic material is added into an organism's genome, with the result of generating a new trait.
Although genetic breakthroughs have defined the 1970's as the era of genetic modification, selective plant breeding is not a new concept. Selection of observed desirable traits by our ancestors essentially cross- pollinated wild plants and made them suitable for agriculture. In the past, if pests devastated a field of crops and numerous plants stayed alive and healthy, the seeds from these healthy plants were used to generate the next crop. Thus the beneficial factors that made the plants were transferred to the next generation, making the new generation of crops slightly more resistant to the same pests. Such selections have been used for over 10,000 years, since the beginning of agriculture, resulting in significant advances for humanity with the increased yields, disease resistance and, overall, greater productivity (Freidmann, 2000).
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As technology continued to evolve, the complexity of genetic modification did also, and thus, coupled with the enhancements of the twenty- first century, the obvious concerns about potential risks from genetic engineering ignited much public debate.
In recent times, the pros and cons and methods of producing such food as a result of genetically modifying crops, are being made available to the broader public, in order to educate the masses, particularly in light of the upcoming referendum. However, in order to make an informed decision regarding the introduction or outlawing of GMO, it is essential to understand the scientific procedures involved in the production of Genetically Modified Organisms.
What is genetic engineering?
The fundamental principle of genetic engineering is to alter the genes by adding or trading the DNA of an existing organism to create a new genetically modified organism with the desired genotype, characteristic or just to add a new trait. (Fitzsimmons, 2003) The structure and function of an organism can be improved with techniques that modify or deactivate an existing gene. In all cell organisms, genes are positioned in the DNA; the molecule that encodes genetic information. DNA is a double-stranded molecule held together by weak bonds between base pairs of nucleotides.
The sequence and relationship of these particles determines the gene, which contains information about the characteristics of a growing organism. In recent times, scientists have established that if an organism's physical characteristics correlate with the experimental gene, the modification of characteristics can be achieved by altering the genes to create a desired result. This process of gene alteration is the epitome of genetic modification. (Biotechnology Online, 2007)
There are many ways genetic modification can occur, those most prevalent are:
Altering a gene
Adding extra copies of an existing gene or;
Adding genes from other organisms or eliminating a gene
The three main procedures: Genetically modifying crops
When genetically modifying crops, there are three main techniques for performing successful GM.
1. Agrobacterium tumefaciens, the bacterium that lives in soil, proved to be a vehicle that was able to deliver genes to plant cells. This is due to the fact that when a plant is damaged, Agrobacteria can get inside it, and simultaneously feed on chemicals released by the plant cells. From here, the plant cells multiply by transmitting some of the plant DNA into the nuclei of the plant cells. (Wahlquist, 2003). As the plant cells multiply, they make more of the chemicals that the bacteria feed on, and thus, scientists discovered that Agrobacteria can be used to transmit engineered genes into crop plants. Scientists begun to inactivate the genes that Agrobacteria transmitted into and replaced the inactivated genes with their own engineered plant genes, allowing the Agrobacteria to 'sneak' the engineered genes into the plant cells, and voila, the plant has been genetically engineered according to the desires of the scientist (Mill, 2001).
This process of genetically engineering other organisms using Agrobacterium has produced only few modified crops due to the generally limiting nature of the process in terms of the method being unable to work on most major food crops. However, the GMO most prevalent to this process of Agrobacterium is tabacco, and the way in which scientists genetically engineered tobacco plants through an Agrobacterium mediated transformation to produce a protein for a vaccine against amoebiasis - a disease predominantly affecting Central and South America, Africa and Asia (Leigh, 2003).
2. The most successful method of gene modification, the gene gun, was developed in the 1980's. This method involves a gun shooting microscopic DNA- coated gold pellets on to the plants leaves in the chamber. The DNA enters the plant cell's nucleus, giving the cell new characteristics.
This method of "insertion technology" was used just in 2004, when genetic engineers were attempting to create a transgenic plant to resolve the problem of BT corn farmers; the insect, corn borers. These pests were eating and destroying huge masses of corn crop, and although pesticides were successful in exterminating the corn borers, they were very harmful to the environment and were very expensive (Cauchi, 2003). After trialing various repellents and poisons, genetic engineers uncovered a solution in bacteria, known as Bt. Bacteria. Using enzymes, genetic engineers were able to remove the pest- killing gene out of Bt's genome, and copies were made. Here, the gene gun was used to move the gene into the corn plant's genome (Mill, 2001). Once the Bt gene entered the corn cell, it became part of the DNA in the corn's genome. Thus, the genetically modified cells grew into corn plants, and when the corn borers consumed the corn, they became poisoned. However, this poses the obvious concerns regarding the effect of such poison in relation to the harmless animals, such as honey- bees and ladybirds, the agronomic effects and also the contamination of human food and the effects of the economy.
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Also, in relation to the corn borer becoming resistant to the Bt protein, the Bt protein is the active ingredient of a number of pesticide sprays employed to protect conventional maize. In the decades they have been in use, there has been no verification that the corn borer was becoming resistant to Bt sprays in the field (Syngenta, 2008). However, pests do find ways around plant control mechanisms, and this natural phenomenon occurs regardless of whether the protection is chemical or biological. In order to ensure that the corn borers do not develop an immunity to the Bt protein, planting systems have been established in which Bt corn is grown amidst refuges and blocks of non- Bt corn. Thus, it is very unlikely that the corn borers will develop an immunity to the Bt protein, however, in a rare case that they did, the corn borers are likely to mate with non- resistant moths from the conventional corn, and ultimately the resistance will not be passed on to future generations (Nottingham, 2007)
3. The third method of genetic modification, electroporation, was designed in 1990. The method of electroporation involves pushing engineered genes through the pores of plant pollen through a significant increase in the electrical conductivity and permeability of the cell plasma membrane, caused by an externally applied electrical field. It is used to introduce substance into a cell by loading it with a molecular probe, a drug that can change the cell's function, or a piece of coding DNA (Purves et. al., 2001).
In reference to genetically modifying crops, electroporation was used recently in Latin America, where coffee is a very important crop. Coffee is susceptible to different kinds of biotic stresses that affect yield significantly. In the cases where coffee does not have natural resistance for pests such as leaf miner (Leucoptera coffeella) or the coffee berry borer (Hypothenemus hampei), the genetic engineers used this system for the genetic transformation permitting the incorporating of resistance to those insects (Gaitan, 2002). Therefore, in 1994, they were able to insert the genetic sequence for insect resistance, into the nucleus of the coffee plant.
However, like the corn borers in 'insertion technology', the previously mentioned leaf miner and coffee berry borer pose the threat of becoming resistant to the gene that is meant to repel them and if such insects spread, they could create destruction amongst crops and other plants for which the bacteria would provide a naturally-occurring protection; a predicament that would be particularly concerning to farmers, and could also ravage wild flora.
Evaluating the environmental, social and ethical issues
Advocates of genetically modified plants emphasise their many benefits over conventional crops such as increased crop yields, decreased pesticide use, enhanced nutritional value. It is essential to note that all information supporting GMOs is going to contain bias. In comparison, the critics of GMOs are going to publish information objecting to the pocesscite just as many risks like harm to other organisms, cross-pollination with conventional plants, the spread of new "superweeds" and "superpests". Therefore, it is crucial that the principal claims of each camp in relation to the environmental, social and ethical issues be profiled:
Socio- Economic issues
- Increase in food production for growing population
- Eliminating malnutrition in impoverished countries by increasing the yield of such crops as rice, which feeds millions in Asia, and cassava, a tuber frequently eaten in Africa. There are two main ways that GMOs can increase crop yields: by creating pest-resistant GMOs, scientists are able to reduce crop losses to pests, especially in developing countries that do not have adequate funds for expensive insecticides and by enhancing the vitamin quality and amount of a widely popular crop.
- Unknown consequences of uncontrollable spread of trangenes into native species, plants, animals and the effect on the food web, with ultimately humans at the top of the food chain: The modified genes may be harmful to another organism, as such, a gene for a bacterial toxin inserted into corn proved poisonous to monarch butterfly larvae that ate the leaves of those plants (Cornell University, 2007). Also, the food chain would be gradually damaged, as this poison would have a domino effect in the way that everyone in the food chain would become slowly affected.
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Allergies: Often, genetically modified plants can inadvertently cross-pollinate with other plants, which is very dangerous as ultimately humans may consume food that has unknowingly and unintentionally cross- pollinated with a GM crop, thus they will adopt any side- effects and allergies from doing so. An example of this was in Mexico, when transgenes were discovered in corn that farmers had not intended for genetic modification. This corn grew at some distance from a field of GM corn- a greater distance than scientists had assumed for pollination. (Encarta, 2008).
http://www.ca.uky.edu/entomology/entfacts/ef130.asp (monarch, 2009)
http://www.wisegeek.com/what-is-bt-corn.htm (wiseweb, 2007)
http://www.extension.umn.edu/distribution/cropsystems/dc7055.html (wiseweb, 2009)
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