Meiosis only occurs in the testesThe plural form of testis, the male organ that produces sperm. and ovariesA pair of organs in the female reproductive system where ova (eggs) and hormones are produced., producing gametes (sperm and egg cells).
This is known as reduction division.
One diploid A cell that contains the normal number of chromosomes. cell produces four haploidA cell that contains half the normal number of chromosomes. gametes, in two divisions.
Human sex cells contain one chromosome Genetic structures that usually occur in functional pairs in the nucleus of cells (except gametes and bacteria). from each of the 23 pairs.
The four gametes produced in meiosis are genetically different.
The process of independent assortment A process that takes place during meiosis, in which chromosomes are reassorted. leads to all gametes being different.
Independent assortment and the random nature of fertilisation lead to variation in living organisms 鈥 no two organisms are the same (apart from identical twins).
During fertilisation the haploid nucleus of a sperm cell and the haploid nucleus of an egg cell fuse together to form a diploid zygote.