For many years artificial selection has been used to produce better quality animals and plants to provide better yield and better quality of meat, milk, vegetables, fruits, etc. But it has been 40 years since genetic engineering had started and has slowly become part of our lives. Genetic Engineering is the process of modifying a genome (the entire gene structure in a chromosome) of a particular organism by adding a gene from a different organism whether from same species or not. This modification is also know as genetic modification.
Genetic Engineering can be done by isolating and copying the gene of a donor and then merging it into the genome of the host. The newly formed DNA sequence is called recombinant DNA because it is a combined DNA strand of two different organisms. The organisms are then called Genetically Modified Organisms (GMO). The GMO can then produce new proteins. Genetic Engineering is commonly used in modifying bacteria. The most common example there is that bacteria are used in fermentation to produce human insulin to treat diabetics. Before this, insulin was extracted from animals which was different in structure compared to human insulin.
Genetic Engineering in Bacteria for Insulin
Bacteria have a single chromosome strand and has a bunch of circular DNA structures called plasmids. These plasmids are a vector for genetic engineering because these are used in the process. A single plasmid is first isolated from the bacteria and is copied. Then a small part of the plasmid is cut off from it by the use of restriction endonucleases. Restriction endonucleases are also known as restriction enzymes. These enzymes cut off the part of the plasmid.
Then a human gene which has the genetic code for production of insulin is isolated, copied and cut off in the same manner, with the help of restriction enzymes. The gene is then merged with the plasmid structure with the help of DNA ligases which are also enzymes but act as a “glue”. The plasmid is then placed back into the bacteria. The bacteria is then fermented to produce insulin in large scale.
The reason bacteria are more commonly used is because the bacteria reproduce quickly and have a tendency to produce these proteins rather fast.
Other Methods of Genetic Engineering
Other uses of genetic engineering are:
- The virus bacteriophage attacks bacteria and latches on to it. It places its DNA inside the bacteria and produces more virus particles like itself. The bacteriophage is a vector for genetic engineering. We can genetically modify the virus so that it can genetically modify any bacteria we need.
- A bacterium called Agrobacterium tumafaciens latches on to plant and leaves some of its plasmids in the cells. We can use the bacteria as a vector for genetic engineering. The genetically modified bacteria will release its plasmids in to the cells and that part can be cut off and can be grown into a new GM plant by micropropagation.
- A special apparatus called the Gene Gun can be used. It contains really tiny gold pallets. Its particles are covered with DNA. The gold pallets are shot into the plant tissue. Then that part can be cut off and grown in micropropagation to produce a GM plant.
Genetic engineering is being used around the world commercially because it has a huge amount of advantageous prospects but some scientists disagree with the use of genetic engineering claiming that we have not thought the long term effects of genetic engineering. Some of the harmful effects have been observed.
One such was that GM crops were used to resist the affects of herbicides which could kill weeds. This was going just fine until the crops started to cross pollinate with the weeds. The next generation of “super weeds” were resistant to the herbicides which became a problem for the scientists. Now more advanced herbicides are needed to kill this “super weeds”.
Other then that some biotechnology companies are abusing the use of genetic engineering by using terminating gene to genetically modify the seeds of the crops. Once the crops ripen, their seeds cannot be used to grow another batch of the same crop plant. So the poor farmers have to buy new seeds from the company after each harvest.
Crops are also given genes for killing insects but once they cross pollinate the new generation will have the genes to kill non target insect which damages the biodiversity.
Effects on Health
Some scientists have argued that there are disadvantages of the use of genetic engineering to human health. Two of these are:
- The affects of Allergens on humans is due to the use of GM food. Allergens are chemicals that cause allergy such as hay fever. The GM food are likely to promote the affect of allergens or may even contain an allergen.
- The GM bacteria are tested with antibiotic resistance genes to make sure whether the recombinant DNA is merged or not. This causes the problem which is discussed in previous chapters. The bacteria may develop resistance towards that antibiotic which causes more problems for the scientists who need to produce a better antibiotic to treat the bacterial disease caused by that specific bacteria.
Other then that there are moral or ethical reasons why people are against genetic engineering but it is spreading across the world very fast and is going to be used in future more vastly.