A gamete is a reproductive cell or sex cell that contains only one set of dissimilar chromosomes, or half the genetic material necessary to form a complete organism. In animals, female gametes are called ova or egg cells, and male gametes are called sperm. Ova and sperm are haploid cells, meaning they carry only one copy of each chromosome. During fertilization, a sperm and ovum unite to form a new diploid organism. Gametes are produced through a type of cell division called meiosis, in which a diploid parent cell undergoes one round of DNA replication followed by two separate cycles of nuclear division to produce four haploid cells. Each gamete carries half the genetic information of an individual, and the type of gamete an organism produces determines the classification of its sex.