The nucleus comprise the genetic information of cell. In addition to activities which maintain the cell, nucleus creates copies of itself for new protozoans by either asexual reproduction- using mitosis, or sexual reproduction - using meiosis. A sexual reproduction generally involves fission, or some sort of division of the parent cell into daughter cells. If two daughters are similar in size, it's binary fission. If one's large than the other, it's budding. If there has been multiple mitotic divisions and parent cell divides into more than two daughters, its multiple fission. Some protozoans form gametes that fuse to form a new protozoan. Ciliates have two nuclei: a macronucleus for running the day-to-day functions of cell and a micronucleus for reproduction. Ciliates have a form of genetic mixing, conjugation, not found in the other protozoans.