Sexual Reproduction

Meiosis is a process that occurs in male and female reproductive organs. Meiosis forms sex cells--sperm and eggs. These cells have half the number of chromosomes as the parent cell.

During sexual reproduction, a sperm fertilizes an egg, and the genetic information from the parents is combined. The fertilized egg is called a zygote.

A human sex cell has 23 chromosomes. At fertilization, the chromosomes from the egg and sperm combine to form a zygote with 46 chromosomes.

The zygote contains all the information needed to form a new organism. Every cell of the organism descends from this original cell.