Benefits and Restraints of Genetic Engineering and the Use of Recombinant DNA.

Matthew Driver AS Biology Coursework : Skill I & J

Benefits and Restraints of Genetic Engineering

and the Use of Recombinant DNA

Genetic engineering and recombinant DNA have many useful purposes which benefit humans in many different ways in many different fields. The latest bio-technological breakthroughs allow the use of recombinant or ‘mixed’ DNA to be used more and more and in increasingly safer conditions. However there are still many problems and restrictions with using recombinant DNA such as side-effects or long term changes and the effect a new characteristic will have on its surrounding environment, be it the human body or a whole environmental ecosystem.

Whilst genetic engineering has been beneficial in many ways increasing plant yields or improving human health, the statement, “The use of recombinant DNA can only benefit humans”, can be discussed and in almost all situations it is found not to be true as discussed below.

Genetic engineering is used frequently in the agricultural industry for many purposes :-

For resistance to disease such tobacco mosaic viruses or potato blight. Making plants resistant to such diseases by inserting the correct resistance gene by genetic engineering means that more of the crops grown can be sold and so the farmer makes more money, the main incentive to most industrial processes.

Resistance to the herbicide, glyophosphate can be achieved by genetic engineering. This means that crops can be sprayed with this herbicide and weeds will be killed but the crops will remain healthy, thus saving money and also reducing the need for labour to manually remove weeds.

Plants can be made to produce an insecticide using the Bacillus Thuringiensis bacteria which mass produces the required Bt protein, the coding for which is inserted by genetic engineering using recombinant DNA. The production of this insecticide means that chemical insecticides are not required thus reducing expenditure and not polluting the environment as much. ...

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Plants can also be made to taste better by changing flavour or made to last longer using different genes, meaning that people will buy them more.

Crops can be genetically modified so that they will grow in different conditions for example in hot, arid conditions, meaning that third world countries can grow crops and have a source of income for themselves.

However, there are many problems and issues that arise from this use of recombinant DNA and GM crops:-

Producing herbicide resistant plants encourages the use of environmentally damaging herbicides ad therefore soil becomes less fertile and can affect ecosystems as the poisonous chemicals can drain into rivers and kill fish and plants within rivers. In addition to this, some weeds may develop a resistance to the herbicide and will therefore be very hard to control.

Producing genetic characteristics such as producing the insecticide may damage harmless ecosystems, for example pollen containing the genetic information is blown from an insecticide producing crop to a non-insecticide producing crop which feeds a harmless insect. As the normal plant produces the insecticide due to the new pollen the insects feeding from it will die. This was the case for caterpillars in 1998 when milkweed was contaminated with pollen from corn.

On top of this, the insects that do need killing may develop a resistance to the Bt protein thus making the insecticide ineffective.

From a more general perspective, food chains may be affected with any of the situations described above, as crop yields are increased there is more food for primary consumers and therefore secondary consumers will increase and may eat more of different primary consumers. On the other hand, killing insects may result in less food for species up the food chain and therefore a decline in some species.

Also GM crops can be harmful if eaten by humans. There have been noticeable reductions in the size of brain, liver and kidneys when some GM crops have fed to rats, which have similar DNA to humans. Scientists are currently developing safer and healthier methods but as of yet it is still an ongoing problem with genetically modifying crops to be eaten.

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The medical industry also uses genetic engineering, known as gene therapy in this industry. An example is the production of Alpha-1 antitrypsin which can be inserted into humans who have this deficiency. The protein destroys unwanted protease enzymes and if it is absent these proteases break down lung tissue causing emphysema and break down liver tissue causing cirrhosis.

The patient can be either dosed with alpha-1 antitrypsin or can undergo gene therapy. They can be dosed using transgenic sheep method, in which the correct gene can be extracted from a healthy human and added to the DNA of a sheep. This recombinant DNA is tested using neomycin as a gene marker and can then be injected back into the sheep causing the sheep to produce alpha-1 antitrypsin in its milk and blood plasma which can then be injected into the human. The advantages of this method are that the patient is safer, they don’t have to undergo complex operations or donate tissue for culture. However the dosage would be required frequently and the sheep can be seriously harmed.

Alternatively gene therapy can be used. Liposomes and adenoviruses can be used as the vector into which the DNA coding for alpha-1 antitrypsin is inserted and this can then be sprayed into lungs using nasal sprays. Instead of this retroviruses can be grown in cultures of the patients liver tissue, resulting in the tissue inheriting the correct DNA coding for the alpha-1 antitrypsin. Adenoviruses are very efficient in inserting the vector, but cause toxic side affects, whereas liposomes have less side effects but aren’t as successful at inserting. The problem with retroviruses is that the cells must be actively dividing for the operation to be successful and most human liver and lung cells are not, and so have to be forced to do so, which is harmful to the patient.

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So it becomes clear that gene therapy is not as simple and successful as it may at first seem, as was the case with genetic engineering in agriculture.

In conclusion, I think that genetic engineering and the use of recombinant DNA can be very successful and helpful to humans as long as the implications are considered and as humans we are not guided by the greed for money without considering the consequences.

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