Recombinant DNA technology

• transformed organisms: microorganisms, plants and animals can all be transformed using recombinant DNA technology

  this is called genetic engineering

  transformed organisms can be made using the same technology as in vivo cloning
• e.g. foreign DNA can be inserted into microorganisms to produce the protein insulin:

  • the DNA fragment containing the insulin is isolated using a technique
  • 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 organisms are also known as genetically engineered or genetically modified (GM) organisms
• • 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 embryo, all of the body cells of the resulting transformed animal will end up containing the gene
  • inserting it into the egg cells of females means that when the female reproduces, all the cells 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
• The recombinant DNA technology debate:

  • some people have concerns about transformed organisms
  • but producing transformed organisms can benefit humans in lots of ways
• humanitarians believe that using recombinant technology will benefit people in lots of different ways
• In 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
  • e.g. Golden Rice is a variety of transformed rice - it contains one gene from maize and one gene from a a soil bacterium
• golden rice:

  • the combination of one gene from maize and one from a soil bacterium, together enable to 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 is a shortage of dietary vitamin A
  • e.g. south asia, africa
  • vitamin A deficiency is a big problem in these areas (up to 500 000 children per year worldwide go blind due to vit A deficiency)
• crops can also be transformed to have resistance to pests or droughts

  pest-resistant crops need fewer pesticides, reduces costs and any environmental problems associated with using the chemicals

  drought resistant crops can survive in drought-prone areas with little water
• In industry:

  • industrial processes often use enzymes (biological catalysts)
  • these enzymes can be produced from transformed organisms, so they can be produced in large quantities for less money
  • reducing costs
• e.g. chymosin:

  • (rennin)
  • is an enzyme used in cheese-making
  • it used to be made from rennet (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 without killing any cows
  • some cheese suitable for vegetarians
• in medicine:

  • many drugs and vaccines are produced by transformed organisms using recombinant DNA technology
• e.g. insulin:

  • insulin is used to treat type I diabetes
  • used to come from animal (cow, horse, pig) pancreases
  • this insulin wasn't human so didn't work as well
  • human insulin is now made from transformed microorganisms, using a cloned human insulin gene
• drugs made using recombinant DNA technology can be produced quickly, cheaply and in large quantities - could make them more affordable and so available to more people
• recombinant DNA technology has the potential to be used in gene therapy to treat human diseases
• transformed crops could be used to make vaccines in areas where refrigeration isn't available (vaccines usually need to be stored in fridges) - make vaccines available to more people
• concerns:

  • some people have ethical, financial and social concerns about the use of recombinant DNA technology
  • include anti-globalisation activists who oppose globalisation e.g. the growth of large multinational companies at the expense of smaller ones
  • some environmentalists have concerns about the possible environmental effects of the technology
• In agriculture X:

  • farmers might plant only one type of transformed crop - monoculture
  • could make the whole crop vulnerable to the same disease bc the plants are genetically identical
  • environmentalists are also concerned about monocultures reducing biodiversity - could damage the environment
• • some people concerned about the possibility of 'superweeds' - weeds that are resistant to herbicides - 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
  • can't sell their crops as organic and may lose their income
• in industry X:

  • without proper labelling, some people they won't have a choice about whether to consume food made using genetically engineered organisms
  • some people are worried that the process used to purify proteins from genetically engineered organisms could lead to the introduction of toxins into the food industry
• • 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
  • anti-globalisation activists are against thsi
• in medicine X:

  • companies who own genetic engineering technologies may limit the use of technologies that could be saving lives
  • also, some people worry that this technology could be used unethically
  • e.g. to make designer babies (characteristics chosen by their parents) - currently illegal
• recombinant DNA also creates ownership issues:

  • 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, other 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 patent laws
• biodiversity increases the variety of living organisms in an area - monoculture reduces biodiversity by reducing the number of plant species in an area

  this in turn reduces the number of other species e.g. insects that the area can support