Competent cells

COMPETENT CELLS
  • As the DNA is a very hydrophilic molecule, it won't normally pass through a bacterial cell's membrane. In order to make bacteria take in the plasmid, they must first be made "competent" to take up DNA.
  • This is done by creating small holes in the bacterial cells by suspending them in a solution with a high concentration of calcium.
  • DNA can then be forced into the cells by incubating the cells and the DNA together on ice, placing them briefly at 42oC (heat shock), and then putting them back on ice.
  • This causes the bacteria to take up the DNA.
  • The cells are then plated out on antibiotic containing media.
Last modified: Tuesday, 13 September 2011, 9:22 AM