other topic 4

• Genetic engineering


  The modification of the genome of an organism by the insertion of a desired gene from another organism<|>Enables the formation of an organism with beneficial characteristics
• Genetic engineering process

  
  

  1. DNA is cut at specific base sequences by restriction enzymes to create sticky ends

  2. Vector DNA from bacteria taken out and cut using the same restriction enzymes to create complementary sticky ends

  3. Ligase enzymes join the sticky ends of the DNA and vector DNA forming recombinant DNA

  4. put it back in bacteria where it will then divide rapidly
• Vector

  A structure that delivers the desired gene into the recipient cell e.g. plasmids, viruses
• Benefits of genetic engineering


  • Increased crop yields for growing population e.g. herbicide-resistance, disease-resistance
  • Useful in medicine e.g. insulin-producing bacteria, anti-thrombin in goat milk
  • GM crops produce scarce resources e.g. GM golden rice produces beta-carotene (source of vitamin A in the body)
• Risks of genetic engineering

  • Long-term effects of consumption of GM crops unknown
  • Negative environmental impacts e.g. reduction in biodiversity, impact on food chain, contamination of non-GM crops forming 'superweeds'
  • Late-onset health problems in GM animals and some embyros dont survive
  • GM seeds are expensive. LEDCs may be unable to afford them or may become dependent on businesses that sell them
• Bacillus thuringiensis (Bt)


  Insect larvae are harmful to crops<|>Bt is a bacterium which secretes a toxin that kills insect larvae
• Using genetic engineering to protect crops against insects

  1. The gene for toxin production in Bt can be isolated and inserted into the DNA of crops

  2. Bt crops now secrete the toxin which kills any insect larvae that feed on it
• Benefits of Bt crops

  • Increased crop yields (fewer crops damaged)
  • Lessens the need for artificial insecticides
  • Bt toxin is specific to certain insect larvae so is not harmful to other organisms that ingest it
• Risks of Bt crops

  • Long term effects of consumption of Bt crops unknown
  • Insect larvae may become resistant to the Bt toxin
  • Killing insect larvae reduces biodiversity