Using Recombinant DNA Technology

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Transformed Organisms are made using Recombinant DNA Technology

Microorgansims, plants and animals can all be transformed using recombinant DNA technology. This is called genetic engineering.

Transformed microorganisms can be made using the same technology as in vivo cloning. For example, foreign DNA can be inserted into microorganisms to produce lots of useful protein, e.g. insulin

The DNA fragment containing the insulin gene is isolated.

The DNA fragment is inserted into a plasmid vector.

The plasmid containing the recombinant DNA is transferred into a bacterium.

Transformed bacteria are identified and grown.

The insulin produced from the cloned gene is extracted and purified.

Transformed plants can also be produced. A gene that codes for a desirable protein is inserted into a plasmid. The plasmid is added to a bacterium and the bacterium is used as a vector to get the gene into the plant cells. If the right promoter region has been added along with the gene, the transformed cells will be able to produce the desired protein.

Transformed animals can be produced too - a gene that codes for a desirable protein can be inserted into an early animal embryo or into the egg cells of a female. If the gene is inserted into a very early animal embryo, all the body cells of the resulting transformed animal will end up containing the gene. Inserting it into egg cells means that when a female reproduces, all of her offspring will contain the gene.

Promoter regions that are only activated in specific cell types can be used to control exactly which of an animal's body cells the protein is produced in. If the protein is only produced in certain cells, it can be harvested more easily. Producing the protein in the wrong cells could also damage the organism.

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Recombinant DNA Technology can be used to Benefit Humans

Transformed organisms (microorganisms, plants and animals) can be used in a variety of ways. You need to be able to interpret information about how they are used. Here are some examples:

AGRICULTURE

Agricultural crops can be transformed so that they give higher yields or are more nutritious. This means these plants can be used to reduce the risk of famine and malnutrition. Crops can also be transformed to have pest resistance, so that fewer pesticides are needed. This reduces costs and reduces any environmental problems associated with using pesticides.

For example, Golden Rice is a variety of transformed rice. It contains one gene from a maize plant and one gene from a soil bacterium, which together enable the rice to produce beta-carotene. The beta carotene is used by our bodies to produce vitamin A. Golden rice is being developed to reduce vitamin A deficiency in areas where there's a shortage of dietary vitamin A, e.g. South Asia, Africa. Vitamin A deficiency is a big problem in these areas, e.g. up to 500 000 children per year worldwide go blind due to vitamin A deficiency.

INDUSTRY

Industrial processes often use biological catalysts (enzymes). These enzymes can be produced from transformed organisms, so they can be produced in large quantities for less money, reducing costs.

For example, chymosin (or rennin) is an enzyme used in cheese-making. It used to be made from rennet (a substance produced in the stomach of cows), but it can now be produced by transformed organisms. This means it can be made in large quantities, relatively cheaply and without killing any cows, making some cheese suitable for vegetarians.

MEDICINE

Many drugs and vaccines are produced by transformed organisms, using recombinant DNA technology. They can be made quickly, cheaply and in large quantities using this method.

For example, insulin is used to treat Type 1 diabetes and used to come from animals (cow, horse or pig pancreases). This insulin wasn't human insulin though, so it didn't work quite as well. Human insulin is now made from transformed microorganisms, using a cloned human insulin gene.

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There are Concerns about the use of Recombinant DNA Technology

There are ethical, financial and social issues associated with the use of recombinant DNA technology:

AGRICULTURE

Farmers might plant only one type of transformed crop (this is called monoculture). This could make the whole crop vulnerable to the same disease because the plants are genetically identical. Environmentalists are also concerned about monocultures reducing biodiversity, as this could damage the environment.

Some people are concerned about the possibility of 'super weeds' - weeds that are resistant to herbicides. These could occur if transformed crops interbreed with wild plants. There could then be an uncontrolled spread of recombinant DNA, with unknown consequences.

Organic farmers can have their crops contaminated by wind-blown seeds from nearby genetically modified crops. This means they can't sell their crop as organic and may lose their income.

INDUSTRY

Anti-globalisation activists oppose globalisation (e.g. the growth of large multinational companies at the expense of smaller ones). A few, large biotechnology companies control some forms of genetic engineering. As the use of this technology increases, these companies get bigger and more powerful. This may force smaller companies out of business, e.g. by making it harder for them to compete.

Without proper labelling, some people think they won't have a choice about whether to consume food made using genetically engineered organisms.

Some consumer markets, such as the EU, won't import GM foods and products. This can cause an economic loss to producers who have traditionally sold to those markets.

MEDICINE

Companies who own genetic engineering technologies may limit the use of technologies that could be saving lived.

Some people worry this technology could be use unethically, e.g. to make designer babies (babies that have characteristics chosen by their parents). This is currently illegal though.

Recombinant DNA technology also creates ownership issues. Here are some examples:

There is some debate about who owns genetic material from humans once it has been removed from the body - the donor or the researcher. Some people argue that the individual holds the right to their own genetic information, however, others argue that value is created by the researcher who uses it to develop a medicine or in diagnosis.

A small number of large corporations own patents to particular seeds. They can charge high prices, sometimes including a 'technology fee', and can require farmers to repurchase seeds each year. If non-GM crops are contaminated by GM crops, farmers can be sued for breaching the patent law.

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Humanitarians Think it will Benefit People

Recombinant DNA technology has many potential humanitarian benefits:

Agricultural crops could be produced that help reduce the risk of famine and malnutrition, e.g. drought-resistant crops for drought-prone areas.

Transformed crops could be used to produce useful pharmaceutical products (e.g. vaccines) which could make drugs available to more people, e.g. in areas where refrigeration (usually needed for storing vaccines) isn't available.

Medicines could be produced more cheaply, so more people can afford them.

Recombinant DNA technology has the potential to be used in gene therapy to treat human diseases.

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Gene Therapy Could be Used to Treat or Cure Genetic Disorders and Cancer

Recombinant DNA technology could also be used to treat human diseases. This is known as gene therapy.

HOW IT WORKS:

gene therapy involves altering the defective genes (mutated alleles) inside cells to treat genetic disorders and cancer.

How you do this depends on whether the disorder is caused by a mutated dominant allele or two mutated recessive alleles.

If it's caused by two mutated recessive alleles you can add a working dominant allele to make up for them (you 'supplement' the faulty gene).

If it's caused by a mutated dominant allele you can 'silence' the dominant allele (e.g. by sticking a bit of DNA in the middle of the allele so it doesn't work any more).

Both of these processes involve inserting a DNA fragment into the person's original DNA.

HOW YOU GET THE 'NEW' ALLELE (DNA) INSIDE THE CELL:

The allele is inserted into cells using vectors just like in recombinant DNA technology.

Different vectors can be used, e.g. altered viruses, plasmids or liposomes (spheres made of lipid).

THERE ARE TWO TYPES OF GENE THERAPY:

Somatic therapy - this involves altering the alleles in body cells, particularly the cells that are most affected by the disorder. For example, cystic fibrosis (CF) is a genetic disorder that's very damaging to the respiratory system, so somatic therapy for CF targets the epithelial cells lining the lungs. Somatic therapy doesn't affect the individuals sex cells (sperms or eggs) though, any offspring could still inherit the disease.

Germ line therapy - this involves altering the alleles in the sex cells. This means that every cell of any offspring produced from these cells will be affected by the gene therapy and they won't suffer from the disease. Germ line therapy in humans is currently illegal.

There are also many ethical issues associated with gene therapy. For example, some people are worried that the technology could be used in other ways than for medical treatment, such as for treating cosmetic effects of aging. Other people worry that there's a potential to do more harm than good by using the technology (e.g. risk of over-expression of genes - gene produces too much of the missing protein).