Role of Biotechnology (AQA GCSE Biology): Revision Note

Feeding the world population

• Biotechnology involves the alteration and use of living organisms to produce products for human use

• Some forms of biotechnology have been around for thousands of years e.g. agriculture and selective breeding to produce better foods

• Modern biotechnology techniques include genetic modification and the ability to culture large quantities of microorganisms for food

• Biotechnology may be able to help provide sufficient food for the increasing human population

Mycoprotein – the process of creating food from a fungus

• The fungus Fusarium is cultured (grown) on an industrial scale in fermenters

• These fermenters are large vats that can be kept at the optimum pH and temperature for Fusarium to grow

  • The use of a water jacket enables a constant temperature to be maintained

• The fungus is grown in aerobic conditions (it is provided with oxygen) and provided with glucose syrup as a food source (to allow the fungus to respire)

  • The paddle allows the reaction mixture to remain aerated and allows reactants to mix thoroughly

• The fungus grows and multiplies within the fermenter

• The fungal biomass is then harvested and purified to produce mycoprotein

• Mycoprotein is a protein-rich food suitable for vegetarians

• For example, it is used in Quorn^TM products

Diagram of a fermenter

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Production of insulin

• Genetic engineering is changing the genetic material of an organism by removing or altering genes within that organism, or by inserting genes from another organism

• The organism receiving the genetic material is said to be ‘genetically modified’, or is described as a ‘transgenic organism’

• The DNA of the organism that now contains DNA from another organism as well is known as ‘recombinant DNA’

• The gene for human insulin has been inserted into bacteria which then produce human insulin which can be collected and purified for medical use to treat people with diabetes

Genetic modification of bacteria to produce human insulin

• The gene that is to be inserted is located in the original organism – the gene for insulin production is located within a human chromosome

• Restriction enzymes are used to isolate or ‘cut out’ the human insulin gene, leaving it with ‘sticky ends’ (a short section of unpaired bases)

• A bacterial plasmid is cut by the same restriction enzyme leaving it with corresponding sticky ends (plasmids are circles of DNA found inside bacterial cells)

Diagram of a restriction enzyme cutting DNA

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• The plasmid and the isolated human insulin gene are joined together by DNA ligase enzyme

  • If two pieces of DNA have matching sticky ends (because they have been cut by the same restriction enzyme), DNA ligase will link them to form a single, unbroken molecule of DNA

• The genetically engineered (recombinant) plasmid is inserted into a bacterial cell

Diagram of a recombinant plasmid being inserted into a bacterium

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• When the bacteria reproduce the plasmids are copied as well and so a recombinant plasmid can quickly be spread as the bacteria multiply and they will then all express the human insulin gene and make the human insulin protein

• The genetically engineered bacteria can be placed in a fermenter to reproduce quickly in controlled conditions and make large quantities of the human protein

GM crops

• Crops can be genetically modified (they are known as GM crops)

• Crop plants, such as wheat and maize, have been genetically modified to contain a gene from a bacterium that produces a poison that kills insects, making them resistant to insect pests such as caterpillars. This can improve crop yields

• Crop plants have also been genetically modified to make them resistant to certain herbicides (chemicals that kill plants), meaning that when the herbicide is sprayed on the crop it only kills weeds and does not affect the crop plant

• Some crops have been genetically modified to produce additional vitamins and improved nutritional value, e.g. ‘golden rice’ contains genes from another plant and a bacterium which make the rice grains produce a chemical that is turned into vitamin A in the human body, which could help prevent deficiency diseases in certain areas of the world

• Some have been genetically modified to be drought-resistant (to grow better in very dry conditions). This can also improve crop yields