Bacterial Transformation (College Board AP® Biology)

Bacterial Transformation

• Bacterial transformation is a technique that modifies the genome of bacterial cells in order to produce a useful protein that is not bacterial in origin

• The best known example is the gene for human insulin that can be inserted into bacterial plasmid

  • 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 bacterial cells which then produce human insulin which can be collected and purified for medical use to treat people with diabetes

  • Specialised fermenters are then used to reproduce bacteria 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 animals 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

Production of Insulin by Bacterial Transformation Diagram

Production of human insulin