DNA extraction/Separation is the first step in the genetic engineering process. This is accomplished by taking a sample containing the gene of interest (the Bacillus thuringiensis ) and taking it through a series of steps that separate the DNA from the other parts of a cell.
During DNA extraction, all of the DNA from the organism is extracted at once. This means the sample of DNA extracted from the Bacillus thuringiensis bacteria will contain the gene for the Bt protein, but also all of the other bacterium’s genes. Scientists use gene cloning to separate the single gene of interest from the rest of the genes extracted.
Once a gene has been cloned, genetic engineers begin the third step, designing the gene to work once inside a different organism. This is done in a test tube by cutting the gene apart with enzymes and replacing certain regions.
The modified gene is now ready for the fourth step in the process, transformation or gene insertion.
Since plants have millions of cells, it would be impossible to insert a copy of the transgene into every cell. Therefore, tissue culture is used to propagate masses of undifferentiated plant cells called a callus. These are the cells to which the new transgene will be added.
The new gene is inserted into some of the cells using various techniques. Some of the more common methods include the gene gun, agrobacterium, microfibers, and electroporation. The main goal of each of these methods is to transport the new gene(s) and deliver them into the nucleus of a cell without killing it.
The new DNA may or may not be successfully inserted into a chromosome. The cells that do receive the new gene are called transgenic and are selected from those that are not transgenic. Many types of plant cells are totipotent meaning a single plant cell can develop into an entire plant. Therefore, each transgenic cell can then develop into an entire plant that has the transgene in every cell. The transgenic plants are grown to maturity in greenhouses and the seed they produce, which has inherited the transgene, is collected.
THE NEED FOR GM MAIZE
The need for GM Maize was to prevent pests such as the European corn borer from destroying crops. By Genetically Modifying Maize to express the bacterial Bt toxin, this preventing the Eurpoean corn borer and other pests from destroying crops. This was achieved
- Previously, traditional pesticides used on Corn corps had to be made concentrated and be made stronger and be sprayed more frequently to kill insect pests such as the Eurpoean corn borer, which was the main culprit in destroying crops.
- With every spray, these pests were getting stronger and building up immunity to the pesticides due to natural selection.
- By inserting a gene from the microorganism Bacillus thuringiensis (Bt) into the corn genome. The gene codes a toxin that causes the formation of pores in the pest’s digestive tract. These pores allow naturally occurring enteric bacteria, such as E. coli and Enterobacter, to enter the circulatory system, it binds to the gut wall and the insect stops feeding. Within hours, the gut wall breaks down and normal gut bacteria invade the body cavity. The insect dies of septicaemia as the bacteria multiply in the blood.
Potential Technology Impact of Bt Corn
| Advantages | Disadvantages |
| The development of pest-tolerant plants can reduce the use of pesticides, which is economically beneficial for farmers. | Not enough is known about whether pesticides built into plants are safe for human consumption. |
| Engineered plants have the potential to rapidly improve crop productivity. | There’s a risk that genetically engineered genes could be introduced into wild plants, reducing biodiversity and creating super-weeds. |
| ETHICAL ISSUES | FOR | AGAINST |
| Is it ethical to interfere with nature? | Many new discoveries are considered to be a threat at first but can be beneficial to society and the environment. If we are able to produce products that are of benefit, it would be unethical not to develop them. |
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| Is it ethical to put a price on genetically modified products to sell? | Financial gain is essential as money can be put back for further research. | People in third world countries may not be able to afford or have access to beneficial GM products making them even poorer and widening the poverty gap between developed countries. |
| BIOLOGICAL ISSUES | FOR | AGAINST |
| If we are able to make products that could bring medical benefits and improve the health and quality of life for humans would it be unethical not to do so, even if we are unsure of the consequences? | Foods with the higher nutritional value may be developed to supply better nutrition to people in third world countries | Potential long term health risks of GM products are not known yet |
| Why is Bt corn still not accepted by some people even though it is effective? | Bt corn is popular with many growers and farmers because it is effective in killing pests, protecting yields, improved grain quality and economically favoured. | Bt corn is still not accepted by some people as even though it is harmless for non-target pollinators such as honey bees and lady bugs, although it indirectly affected the monarch caterpillars |
