Although sexual reproduction involving the fusion of cells (gametes) does not occur in bacteria, genetic material is sometimes exchanged between bacteria. This is done in three different ways. The first method is a transformation in which fragments of DNA are released by a broken cell and taken in by another bacterial cell. The second possibility is transduction, in which a bacteriophage (a virus that infects and replicates within a bacteria) carries genetic material from one bacterial cell to another. The last possibility is conjugation, in which two cells of different mating types come together and exchange genetic material.