Biological life cycle

A life cycle is a time of development of one generation of a species, whether through asexual reproduction or sexual reproduction, and especially in regard to its ploidy. There are three types of cycles:

Related Topics:
Generation - Species - Asexual reproduction - Sexual reproduction - Ploidy

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• haplontic life cycle
• diplontic life cycle
• diplobiontic life cycle (also referred to as diplohaplontic, haplodiplontic or dibiontic life cycle)

These three types of cycles feature the alternating haploid and diploid phases (n and 2n). The haploid organism becomes diploid through fertilizations of gametes, resulting in a zygote (see Reproduction). To return to the haploid stage, meiosis occurs (see Cell division).

Related Topics:
Haploid - Diploid - Fertilization - Gamete - Zygote - Reproduction - Meiosis - Cell division

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The cycles differ in the product of meiosis, and if mitosis (growth) occurs. Zygotic and gametic meiosis have one mitotic stage and form: during the n phase in zygotic meiosis and during the 2n phase in gametic meiosis. Therefore, zygotic and gametic meiosis are collectively term haplobiontic (single meiosis per phase). Sporic meiosis, on the other hand, has two meiosis events (diplobiontic): one in each phase.

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Biological life cycle: Haplontic life cycle ►