Introduction:
At some point in time, we have all heard something about Genetically Modified crops. However, what are these Genetically Modified crops, and what does it mean to modify something genetically?
Genetic modification, also known as genetic engineering, is a process that uses recombinant DNA (rDNA) technology to alter the genetic makeup of an organism. In simple terms, genetic engineering is when we modify the “code” of an organism or a population of organisms. Since the DNA (the code) is responsible for creating the proteins synthesised by an organism, modifying an organism’s DNA causes a change in the synthesised proteins. An organism generated through genetic engineering is known as a Genetically Modified Organism (GMO).
Genetic engineering has its applications in multiple spheres, such as medicine, research, industry, or its most widespread use in agriculture. For example, in medicine, genetic engineering has been used to mass-produce insulin, human growth hormones, Follistim (for treating infertility), human albumin, monoclonal antibodies, antihemophilic factors, vaccines, and drugs. In addition, genetic engineering is utilised to create models of animals for drug testing. Furthermore, it serves as a vital component in experimental treatments like gene therapy. Moreover, it has proved to be a valuable tool for scientists to experiment with transgenic organisms (organisms with foreign DNA).
These experiments are conducted to understand the functions of specific genes and their effect on the organism’s phenotype. Through genetic engineering, researchers can also understand how particular genes and their expressions (Gene expression is the process by which the instructions in our DNA are converted into a functional product, such as a protein.) interact with each other.
Various industries like the agricultural industry employ genetic engineering for producing seeds that increase crop production and tolerance to biotic and abiotic stressors (diseases, heat, drought etc.) Though it is the application where there is still a large amount of debate on its safety and the entire ethics of gene engineering.
Methods of Genetic Engineering:
Genetic engineering can take place through 3 methods: Recombinant DNA, Gene delivering, and Gene Editing.
Recombinant DNA technology was the first method developed to engineer organisms genetically in seven steps. The stages of the process are:
1. Isolation of the Genetic Material (DNA)
Since the DNA is enclosed within the membranes, to release it and other macromolecules, the tissues are treated with an enzyme to extract the genetic material.
2. Cutting of DNA at Specific Locations
The required portion of the DNA is cut using specific enzymes to ensure that only that portion is edited and amplified later.
3. Isolation of Desired DNA Fragment
Once cut, the DNA fragment is isolated and extracted through a process known as Gel Electrophoresis.
4. Amplification of Gene of Interest using PCR
The gene is then cloned through a process known as Polymerase Chain Reaction to create duplicates of that DNA fragment.
5. Ligation of DNA Fragment into a Vector
This process requires a vector DNA and a source DNA. Firstly, the gene of interest is cut using biological scissors. Secondly, all components (vector DNA, gene of interest and enzyme DNA ligase) are combined to form the recombinant DNA.
6. Insertion of Recombinant DNA into the Host Cell/Organisms
The ligated DNA is then inserted into the Host Cell/Organism to be multiplied.
7. Obtaining or Culturing the Foreign Gene Product
The multiplied DNA is then analysed, and the researcher selects the bacteria that contain the gene of interest.
The second method through which genetic engineering can take place is Gene Delivery. This method introduces foreign genetic material, such as DNA or RNA, into host cells. Gene delivery must reach the genome of the host cell to induce gene expression. Successful gene delivery requires foreign gene delivery to remain stable within the host cell. It can either integrate into the genome or replicate independently of it. There are multiple ways through which the delivery can be done: chemical, physical, agrobacterium, and viral vector. The chemical methods include heat shock, application of Calcium Phosphate, liposomes, polymers and nanoparticles. The physical methods include electroporation, biolistics, microinjection, sonoporation, photoporation and hydroporation. Further, the viral delivery involves RNA or DNA based viral vectors.
The third method, known as Genome Editing, is the most recently developed. Genome editing is a type of genetic engineering in which DNA insertion, deletion, modification or replacement occurs in the genome of a living organism. Unlike early genetic engineering techniques that randomly insert genetic material into a host genome, this method targets the insertions to site-specific locations. An example of this process that has recently gained popularity is the CRISPR-Cas9 technology.
CRISPRs (Clustered Regularly Interspaced Short Palindromic Repeats) are genetic elements that bacteria use as a form of acquired immunity for protection against viruses. They consist of short sequences that originate from viral genomes and have been incorporated into the bacterial genome. Cas (CRISPR associated proteins) process these sequences and cut matching viral DNA sequences. Thus, the eukaryotic genome can be cut at any desired position by introducing plasmids containing Cas genes and specifically constructed CRISPRs into eukaryotic cells.
Ethics of Genetic Engineering:
Genetic engineering has been taking place since the early 1970s. Since then, the controversies and opposition to it have steadily risen. The problems with genetic engineering can be divided into four categories: effects on the environment, impact on humans, antibiotic resistance and ethical issues.
The impact of genetic engineering on the environment is generally favourable. Yet, questions over the potential threat of modified organisms to nature persist. For example, the release of a genetically engineered species could cause an imbalance in the ecology of a region. Furthermore, an accident in engineering the genes of a virus or bacteria could create a more potent variety that could cause a severe epidemic if released.
From the perspective of impact on humans, genetic engineering involves using viral vector genes, leading to a health concern for humans. It could also create unknown side effects or outcomes. For example, specific changes in a plant or animal species could cause unpredictable allergic reactions in some people.
The process of genetic engineering often employs the use of genes to create resistance to bacteria. Although the genes have no significant role to play, they continue to be expressed in plant tissues. As a result, a majority of genetically engineered food crops carry these genes.
The presence of these genes in food products could lead to lethal effects on human beings as their consumption would reduce the effectiveness of antibiotics against diseases in the future. Moreover, the resistant genes could be transferred to human or animal pathogens, making them impervious to antibiotics.
The ethical critique of genetic engineering is another reason for its controlled usage. The idea that scientists wish to “Play God” has become a strong argument against genetic engineering. These concerns range from various ethical issues to the lack of knowledge vis-à-vis the effects of genetic engineering. A significant problem is that the modification of a gene is irreversible. Hence, there is a chance that the transformation can cause more harm than benefit to society.
Subsequently, the appeal of genetic engineering towards the general public has been ambiguous. Society appreciates its use in medicine; however, the fear that disease-producing organisms used in some genetic experiments might develop extremely infectious forms that could cause pandemics is ever-present.
The insertion of more and more human genes into non-human organisms has raised numerous questions. For instance, what percentage of human genes must an organism contain before it is considered human? Furthermore, considering that human genes are now being inserted into tomatoes and peppers to improve their growth, one can now question whether it is possible to be a vegetarian and a cannibal simultaneously?
The use of GMOs for consumption raises a few other issues. For example, the transfer of allergens from one crop to another through genetic engineering is a cause of worry. Another problem is that pregnant women who consume genetically modified foods may put their children at risk by altering fetal gene expression.
Another terrifying scenario is the destructive use of genetic engineering. Rouge states or non-state actors could harness the technology to develop more powerful biological weaponry. These weapons could target entire populations or, in some cases, target those individuals who are carriers of specific genes.
Conclusion:
The possibilities of the future applications of Genetic Engineering are endless. They range from the more realistic ideas about advancing crop technologies to the more absurd ideas of modifying the human genome to create “superhumans”. If we can imagine it, it is in the realm of possibility that we can genetically engineer something akin to that. However, before we begin to educate people and start modifying everything, we need to sort out the quarrel with the environment.
With any new technology, the ecological effects are the most important to consider and alleviate, especially in this current age of high rates of environmental degradation. So at least for the foreseeable future, we won’t have superhumans walking on the face of the planet.
Reference Links:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3722627/
https://www.sciencedirect.com/science/article/abs/pii/S0889858805700046
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7122027/
https://www.nature.com/articles/nprot.2013.143