Change The Dna Of Living Organisms Biology Essay

Published: Last Edited:

This essay has been submitted by a student. This is not an example of the work written by our professional essay writers.

DNA is the blueprint for the individuality of an organism. The organism relies upon the information stored in its DNA for the management of every biochemical process. The life, growth and unique features of the organism depend on its DNA. The segments of DNA which have been associated with specific features or functions of an organism are called genes.

Molecular biologists have discovered many enzymes which change the structure of DNA in living organisms. Some of these enzymes can cut and join strands of DNA. Using such enzymes, scientists learned to cut specific genes from DNA and to build customized DNA using these genes. They also learned about vectors, strands of DNA such as viruses, which can infect a cell and insert themselves into its DNA.

With this knowledge, scientists started to build vectors which incorporated genes of their choosing and used the new vectors to insert these genes into the DNA of living organisms. Genetic engineers believe they can improve the foods we eat by doing this. For example, tomatoes are sensitive to frost. This shortens their growing season. Fish, on the other hand, survive in very cold water. Scientists identified a particular gene which enables a flounder to resist cold and used the technology of genetic engineering to insert this 'anti-freeze' gene into a tomato. This makes it possible to extend the growing season of the tomato.

At first glance, this might look exciting to some people. Deeper consideration reveals serious dangers.

Genetic engineering refers to a set of technologies that are being used to change the genetic makeup of cells and move genes across species boundaries to produce novel organisms. The techniques involve highly sophisticated manipulations of genetic material and other biologically important chemicals.

Genes are the chemical blueprints that determine an organism's traits. Moving genes from one organism to another transfers those traits. Through genetic engineering, organisms are given new combinations of genes-and therefore new combinations of traits-that do not occur in nature and, indeed, cannot be developed by natural means. Such an artificial technology is radically different from traditional plant and animal breeding.

Genetic engineering is any process by which genetic material (the building blocks of heredity) is changed in such a way as to make possible the production of new substances or new functions. As an example, biologists have now learned how to transplant the gene that produces light in a firefly into tobacco plants. The function of that gene-the production of light-has been added to the normal list of functions of the tobacco plants.


Gene Splicing: : The Crick-Watson discovery opened up unlimited possibilities for biologists. If genes are chemical compounds, then they can be manipulated just as any other kind of chemical compound can be manipulated. Since DNA molecules are very large and complex, the actual task of manipulation may be difficult. However, the principles involved in working with DNA molecule genes is no different than the research principles with which all chemists are familiar.

For example, chemists know how to cut molecules apart and put them back together again. When these procedures are used with DNA molecules, the process is known as gene splicing. Gene splicing is a process that takes place naturally all the time in cells. In the process of division or repair, cells routinely have to take genes apart, rearrange their components, and put them back together again.

Scientists have discovered that cells contain certain kinds of enzymes that take DNA molecules apart and put them back together again. Endonucleases, for example, are enzymes that cut a DNA molecule at some given location. Exonucleases are enzymes that remove one nitrogen base unit at a time. Ligases are enzymes that join two DNA segments together.

It should be obvious that enzymes such as these can be used by scientists as submicroscopic scissors and glue with which one or more DNA molecules can be cut apart, rearranged, and the put back together again.

Vector: The second method of genetic engineering is called the vector method. It is similar to the plasmid method, but its products are inserted directly into the genome via a viral vector. The preliminary steps are almost exactly the same: cut the viral DNA and the DNA to be inserted with the same enzyme, combine the two DNA sequences, and separate those that fuse successfully. The only major difference is that portions of the viral DNA, such as those that cause its virulence, must first be removed or the organism to be re-engineered would become ill. This does yield an advantage - removal of large portions of the viral genome allows additional "space" in which to insert new genes.

Once the new viral genomes have been created, they are allowed to synthesize protein coats and then reproduce. Then the viruses are released into the target organism or a specific cellular subset (for example, they may be released into a bacterium via a bacteriophage, or into human lung cells as is hoped can be done for cystic fibrosis patients). The virus infects the target cells, inserting its genome - with the newly engineered portion - into the genome of the target cell, which then begins to express the new sequence.

With vectors as well, marker genes such as genes for antibiotic resistance are often used, giving scientists the ability to test for successful uptake and expression of the new genes. Once again, the engineered organisms can then be used in experiments or in industry. This technique is also being studied as a possible way to cure genetic diseases (see Genetic Engineering Debates).

Many people object to this type of genetic engineering as well, citing the unpredictability of the insertion of the new DNA. This could interfere with existing genes' function. In addition, many people are uncomfortable with the idea of deliberately infecting someone with a virus, even a disabled one.

Organisms that are genetically mofidied

Fish Grow Four Times Faster on Animal Pharm

In the television documentary Animal Pharm the presenters attempt to balance the arguments for and against genetic manipulation. One segment within the first of a two part documentary shows salmon that grow four times faster than normal in their first year of life.

The program, screened on ABC in Australia, case studies a variety of different types of genetic manipulation from the selective breeding (normal practice in modern farming) through to transgenics - the ability to identify individual genes, extract them and then move genes between species. Various types of procedure in pigs, chickens, cattle and horses are reviewed as well as genetic manipulation in aquaculture.

Looking at the 'pharmed' salmon and the non GM salmon swimming side by side in the same tank is amazing. The bulk of the fish with the transgene present is astounding.

The work to produce the high growth salmon has been conducted by Mr Joe McGonigal. The fish with the transgene grows faster during its first year of life.

Normally salmon grows in warmer water. McGonigal has taken a gene which controls growth from a fish that is a cold water species. By introducing this gene to the Super Salmon, the fish are able to grow year round - whatever the temperature.

McGonigal justifies his work by pointing out the food conversion ratio efficiencies in the genetically manipulated fish. He claims a 30% higher weight gain per gram of feed over non GM salmon.

He points out that the salmon have been created sterile to negate the chance of potential escapees interbreeding with wild stocks.

Could this be part of the solution required to break the nexus between limits on our ability to sustainably supply fish meal and filling the global fish production gap?

Information about the the program is presented here.

What other examples of genetic manipulation for growth promotion in fish exist? Are their species other than salmon in which similar work has been conducted? What conditions must be met for safe practice?

Are there any other resources that you can point to that will help our community of interest appreciate the key issues?

Golden rice

Golden rice is genetically modified rice that now contains a large amount of A-vitamins. Or more correctly, the rice contains the element beta-carotene which is converted in the body into Vitamin-A. So when you eat golden rice, you get more vitamin A.

Beta-carotene gives carrots their orange colour and is the reason why genetically modified rice is golden. For the golden rice to make beta-carotene three new genes are implanted: two from daffodils and the third from a bacterium.


The rice can be considered a particular advantage to poor people in underdeveloped countries. They eat only an extremely limited diet lacking in the essential bodily vitamins. The consequences of this restricted diet causes many people to die or become blind. This is particularly true in areas of Asia, where most of the population live on rice from morning to evening.


Critics fear that poor people in underdeveloped countries are becoming too dependent on the rich western world. Usually, it is the large private companies in the West that have the means to develop genetically modified plants. By making the plants sterile these large companies can prevent farmers from growing plant-seed for the following year - forcing them to buy new rice from the companies.

Some opposers of genetic modification see the "golden rice" as a method of making genetic engineering more widely accepted. Opponents fear that companies will go on to develop other genetically modified plants from which they can make a profit. A situation could develop where the large companies own the rights to all the good crops.

Ethical/moral issues with genetic modification

Transgenics and genetic engineering present intriguing and difficult challenges for 21st century scientists and ethicists. Until we as a society or, perhaps, as a global entity can agree on what beings, human or otherwise, are worthy of moral and legal status and respect, we can expect intense cross-disciplinary debate and discussion as new intelligent life is created through science and medicine.

Ethical issues

The direct genetic modification of plants used in food production has raised public concerns over food safety, environmental risks and socio-economic effects as well as intrinsic concerns about human intervention in nature. There are likely to be additional concerns over direct genetic modification in animals.

Most people accept the use of animals for a range of purposes including food production, providing that the animals are treated humanely. In 1994 the UK government established a committee to consider the ethical implications of the use of new breeding technologies in farm livestock (the 'Banner Committee'), and it has since accepted the major recommendations of that committee. The Banner Committee suggested that the humane use of animals respect three principles:

some treatments of animals are so harmful that they should never be permitted under any circumstances;

if a harmful treatment is permitted, the harm it causes must be justified by the good being sought,

steps should be taken to minimise any harm which is justified by the second principle.

The first principle would exclude the use of technologies, which are regarded as intrinsically objectionable. (There are many new technologies which are not intrinsically objectionable, and which may offer benefits for society or for animals e.g. by improving resistance to disease. Conversely, conventional selection techniques sometimes result in changes which many people regard as objectionable e.g. the extreme breast development, and associated difficulties with natural mating, seen in some strains of turkey.)

Both the creation of genetically modified organisms, and breeding from them, are controlled procedures already in the UK, requiring a licence from the Secretary of State. Before a licence is granted, the likely 'adverse effects' on the animal have to be weighed against the likely benefits of the modification.

It seems appropriate that any analysis of the technical aspects of livestock breeding technologies is accompanied by an analysis of the ethical implications. The framework and recommendations of the Banner Committee provide an important foundation for this, and for a more open dialogue in an area of public concern. In the longer term, this should help to restore public confidence in farming and science, whilst allowing maximum benefit to be derived from those technologies which are considered acceptable.