Conjugation

For conjugation in grammar, see Verb.

Conjugation is a temporary union of two organisms for the purpose of DNA transfer. Conjugation is most common in bacteria, and is a major factor in horizontal gene transfer. Conjugation between two cells of the same bacterial species involves a thin tube joining the cells and transferring DNA, but when two different species are involved the bacteria form a larger structure called a protoplast, where the cell walls form the bridge between the cells.