Competent cell
From Biocrawler, the free encyclopedia.
Competent cells are bacteria which can accept extra-chromosomal DNA. Cells can be made competent in several ways. One such way is to "shock" it, which involves heating the bacteria in a Calcium Chloride bath at 0 degrees Celsius, then quickly heating it to 47 degrees Celsius. The calcium chloride ions neutralize the repulsion between the negatively charged phospholipid heads of the cell membrance, and the negatively charged phosphate groups on the DNA. The quick heat shock creates a thermal gradient which, in turn, creates a draft leading into the cell, allowing extra-chromosomal DNA (such as plasmids) to enter the cell, allowing the bacterium to be genetically modifed.
See also: Transformation (genetics)
