Bacteria are able to take up DNA from their environment by three ways; conjugation, transformation, and transduction. In transformation the DNA is directly entered to the cell. Uptake of transforming DNA requires the recipient cells to be in a specialized physiological state called competent state. Natural competence was first discovered by Frederich Griffith in 1928. It is highly regulated in bacteria, and the factors involved in competence vary among genera. The competence proteins produced have some homology but differ in the Gram negative and the Gram positive bacteria. Once the DNA has been brought into the cell's cytoplasm, it may be degraded by the nuclease enzymes, or, if it is very similar to the cells own DNA, the DNA repairing enzymes may recombine it with the chromosome.