What process do organisms go through to produce sex cells?

Organisms go through the process called meiosis to produce sex cells. During meiosis, one parent cell is divided into four gametes. This is made possible because there are two rounds of division that occur during meiosis. However, the genetic material of the parent cell is only replicated once. Thus, the four gametes that result only have half of the genetic material that the parent cell has. In other words, meiosis results in four haploid gametes.

Two gametes, a sperm and an egg, combine during the process of fertilization to create a zygote. The fact that gametes are haploid ensures that the number of chromosomes that is unique to a species is maintained generation after generation. For example, a somatic (body) cell of humans contains 46 chromosomes. Each gamete of a human contains 23 chromosomes. Thus, upon fertilization, the diploid number of 46 chromosomes is restored.