Bacterial Transformation (College Board AP® Biology): Study Guide

Bacterial transformation

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

  • It involves introducing new DNA into bacterial cells

  • Bacteria that contain new DNA are said to have been transformed

• Bacterial transformation occurs during:

  • the insertion of human genes into bacterial cells, e.g. the gene for human insulin

    1. The insulin gene is inserted into bacterial plasmids, which act as DNA vectors

    2. Bacteria take up the plasmids and are transformed

    3. The gene can then undergo transcription and translation to produce human insulin

  • in vivo gene cloning; this uses living cells to propagate DNA fragments for scientific study

    1. Vectors are used to carry a DNA fragment into bacterial cells, which are transformed

    2. The bacteria reproduce, resulting in many identical offspring that all contain copies of the DNA fragment

• Bacteria are extremely useful for DNA manipulation because:

  • The genetic code is universal across all types of organisms, meaning that transformed bacteria can easily produce proteins from other species

  • There are no ethical concerns over the manipulation of bacterial DNA

  • The presence of plasmids, which are separate from the main bacterial chromosome, means that they can act as convenient DNA vectors