The Process of Genetic Engineering (OCR Gateway GCSE Biology: Combined Science)

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The Process of Genetic Engineering

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  • The gene that is to be inserted is located in the original organism
  • Restriction enzymes are used to isolate the required 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)
  • This plasmid is a vehicle used to introduce the new DNA into a host and is referred to as a vector
  • During the genetic modification process, a gene providing resistance to an antibiotic can be inserted into GM plants as a marker, which is linked to the new gene with a desirable trait
  • Scientists can then use this marker to select the insertion point of the new gene

Restriction enzymes, IGCSE & GCSE Biology revision notes

Restriction enzymes cut DNA strands at specific sequences to form ‘sticky ends’

  • The plasmid and the isolated 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

Recombinant plasmids, IGCSE & GCSE Biology revision notes

DNA ligase is used to join two separate pieces of DNA together

  • The genetically engineered plasmid vector is inserted into a bacterial cell
  • 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 gene and make the human 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
  • In the context of agriculture and food production, the recombinant crop plants can be planted out in the fields and looked after just as before
    • Farmers will see the benefits in the form of yield and/or crop qualities

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Author: Phil

Phil has a BSc in Biochemistry from the University of Birmingham, followed by an MBA from Manchester Business School. He has 15 years of teaching and tutoring experience, teaching Biology in schools before becoming director of a growing tuition agency. He has also examined Biology for one of the leading UK exam boards. Phil has a particular passion for empowering students to overcome their fear of numbers in a scientific context.