The zygote's genome is a combination of the DNA in each gamete, and contains all of the genetic information necessary to form a new individual. In multicellular organisms, the zygote is the earliest developmental stage. In single-celled organisms, the zygote can divide asexually by mitosis to produce identical offspring.
In humans, zygotes are formed when a male gamete, formally called a spermatozoon, fuses with a female gamete, called an oocyte. This process is called fertilization. ... Exhausted, the sperm releases its chromosomes into the interior of the egg cell, while its outer membrane fuses with that of the egg cell.
