Meiosis and its key features

Sexual reproduction joins two gametes, each carrying a full haploid set of chromosomes. The gametes come from special diploid cells.

Meiosis is the special division that halves the chromosome number and so produces haploid daughter cells. It creates the haploid phase of the life cycle, and fertilisation restores the diploid phase.

Meiosis happens during gametogenesis in plants and animals and gives rise to haploid gametes.

It has two successive rounds of nuclear and cell division, meiosis I and meiosis II, but only one round of DNA replication.

Meiosis I begins after the parent chromosomes have replicated in S phase to give identical sister chromatids.

Homologous chromosomes pair, and recombination takes place between non-sister chromatids of the homologues.

At the end of meiosis II there are four haploid cells.

Each division has four stages: prophase, metaphase, anaphase and telophase I in meiosis I, and prophase, metaphase, anaphase and telophase II in meiosis II.