Genetic modification is one of the most controversial topics in all of modern science and with the advancement of synthetic biology over the last decade or so it is sure to become even more of a talking point in the future. Genetic modification is a subject that most people seem to have an opinion on, but I must say that a great deal of those opinions are built upon misconceptions or influenced by the charm of organic propaganda. I cant help but find such misunderstandings quite ironic, for example, the man who strongly opposes the consumption of genetically modified foods, yet requires the injection of insulin produced via genetically modified micro-organisms to keep his diabetes under control, to name just one such example. It seems that people like to argue when they’re aware of an argument. People often fail to realize the extent to which this technique has been practiced and honed, it seems rather absurd that people are still insisting that these scientists are tampering with genes without any knowledge of what ‘may’ happen. Absurd.
Genetic modification is such a broad and diverse subject, I only wish to discuss a few particular aspects, but more information is obviously available in abundance from a range of other sources.
Modifying GenesThe modification of genetic material relies upon the idea of basic cloning; cloning your desired gene into a new organism where it is to be over-expressed. Basic cloning can be broken down into several steps. Firstly, the insertion of a DNA fragment into a vector to form a recombinant molecule. The recombinant molecule is then transported into a bacterial cell (E.coli is widely used). Following that, the bacterial cell is multiplied (subsequently multiplying copies of the recombinant molecule inside) and then bacterial colonies are produced that contain the recombinant molecule . Notably, this procedure of basic cloning requires the use and extensive knowledge of various types of enzymes such as nucleases, ligases and polymerases; I won’t delve into their description here .
The ‘vector’ or cloning vector that is used to transport the gene of interest into the bacterial cell (mentioned in the previous paragraph) are normally one of two types; either plasmid cloning vectors or bacteriophage cloning vectors . Firstly, plasmid cloning vectors. Plasmids are autonomous, closed circular, double-stranded DNA molecules that are found in prokaryotes and they range in size from 1000 base pairs to about 200,000 base pairs . It is important to add that most plasmids that are used as vectors have themselves been modified to make them more convenient and versatile as a vector. Desirable characteristics of plasmid-cloning vectors include: small size, high copy number, range of unique restriction sites (sites at which the plasmid is cleaved) and a selectable marker. An example of a selectable marker would be antibiotic resistance, as when the bacteria (containing the plasmid) are cultured they can be treated with antibiotics, resulting in the death of all the bacterial colonies apart from the colonies containing the plasmid (enabling easy identification of the bacteria containing the recombinant molecule) . An important requirement of plasmid cloning vectors (and any cloning vector really) is that the selectable marker is easily recognizable and that it contains unique restriction sites, so that when the plasmid is treated with restriction enzymes the fragments can be easily identified. The other main category of cloning vectors is the bacteriophage cloning vectors. Bacteriophages are simply viruses that infect bacteria . The desirable characteristics of bacteriophage cloning vectors are similar to that of plasmid cloning vectors as is the general mechanism for cloning. Interestingly, ‘cosmid’ cloning vectors have also been developed. Cosmid cloning vectors are a mixture of a plasmid (predominantly plasmid) and a bacteriophage to create an optimal vector .
The enzymes and techniques described above have various important uses within biochemistry and genetic analysis. For example, the bacteriophage-cloning vector named ‘lambda’ and cosmid vectors are used for the construction of genomic libraries; a collection of cloned fragments that together encompass the whole genome of an organism (genes and non-coding DNA). Genomic libraries can then be used to identify and isolate individual clones that contain your gene of interest . Geneticists also create cDNA libraries that contain only the coding regions of a genome by using the mRNA produced in a cell . So, as one would expect genetic modification is often used for genetic analysis. Moreover, the enzymes and general theoretical understanding of these techniques are also important features of (and used in conjunction with) the processes of the polymerase chain reaction (PCR) which is an important technique used to amplify the amount of DNA in a sample; applications of which include DNA fingerprinting, cloning and others . The technologies were also pivotal in the development of chain termination (or Sanger) sequencing that was used to map the human genome back in the 1990s (results published in 2001) .
However, the reason why genetic modification has become a much more mainstream idea is due to the fact that products (proteins) can be made and purified by modified cells or organisms. For example, we can modify the tomato that a plant produces by altering its genes or we can alter the genome of E. coli to such an extent that it now produced biofuel as a metabolic product.
Uses & ImplicationsOne of the most controversial areas of genetic modification normally relates to food products. Should we alter the genetic make-up of a plant to improve the versatility, taste or ‘healthiness’ of its food product? For example, genetically modified rice is consumed in China; the rice is called ‘golden rice’ and has been genetically modified in such a way that it now contains more Vitamin A. People from certain areas of China are deficient in the Vitamin, so the rice was introduced to allow the people an easy way to increase their Vitamin A intake, however the ethical issues regarding the issue are still ongoing . Some people believe that we shouldn’t tinker with the natural products of the Earth, whilst others believe that due to the increasing population here on Earth, GM food is the only way that supply will be able to keep up with future demand. Furthermore, slightly outside the media limelight is the advent of genetically modified medicine, I’ve already mentioned the modification of microorganisms to produce insulin for the treatment of diabetes. Additionally, there are many more examples of this technology being used in similar ways and there hasn’t been any adverse side effects reported yet? In fact, many see genetically modified medicines as the future of modern medicine. Where do you stand? It was only a couple of years ago that reporters were shouting about the invention of an anti-HIV drug from GM tobacco plants.
The future & The Synthetic Biology Crusade!So, I hope you can agree conclusively that genetic modification has a big future whether it is in the development of medicines, foods or fuels (most probably all three in just a few years). However, the front line of genetic modification is fast evolving and ever changing. So much so that we now call modern genetic engineering by a completely different name, this being ‘synthetic biology’. Synthetic biology not only includes the altering of genes and changing of function and products, but the idea of building organisms from the bottom up . Only this month in the New Scientist, Craig Venter declared that he and his team are close to building a complete novel organism . I cant help but put forward that this is the obvious future of genetic modification; the development of new medicines (Jay Keasling and his anti-malarial drug ) and new fuels (Craig Venter producing biofuels from algae ). It is all very exciting, but it begs the question; how long until we live in a genetically modified world? My guess is not too long and it will not be the lack of technology that holds us back, but the ethics. Is this right or wrong? Time will tell.
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