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

The Process of Genetic Engineering

Higher Tier Only

• 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 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

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