• The gene for?human insulin?can be 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)
• 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
• 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
• Bacteria are extremely useful for genetic engineering purposes because:
  • They contain the?same genetic code?as the organisms we are taking the genes from, meaning they can easily ‘read’ it and?produce the same proteins
  • There are?no ethical concerns over their manipulation and growth?(unlike if animals were used, as they can feel pain and distress)
  • The?presence of plasmids?in bacteria, separate from the main bacterial chromosome, makes them?easy to remove and manipulate?to insert genes into them and then place back inside the bacterial cells

   

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