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Diagram of the ways to reprogram cells along with the development of humans. Human cloning is the creation of a genetically identical copy of a human. The term is generally used to refer to artificial human cloning, which is the reproduction of human cells and tissue.
Females can produce full clones of themselves through a modification of the normal meiosis process used to produce haploid egg cells for sexual reproduction. The female's germ cells undergo a process of premeiotic genome doubling, or endoreduplication, so that two consecutive division cycles in the process of meiosis result in a diploid, rather than haploid, genome.
Asexual or clonal reproduction occurs by binary fission. Binary fission involves mitosis-like behavior of the chromosomes similar to that of cells in higher organisms. The sexual forms of reproduction are autogamy, a kind of self-fertilization, and conjugation, a kind of sexual interation between different cells. Clonal asexual reproduction can ...
The term clone is used in horticulture to refer to descendants of a single plant which were produced by vegetative reproduction or apomixis. Many horticultural plant cultivars are clones, having been derived from a single individual, multiplied by some process other than sexual reproduction. [22]
Some species reproduce exclusively by parthenogenesis (such as the bdelloid rotifers), while others can switch between sexual reproduction and parthenogenesis. This is called facultative parthenogenesis (other terms are cyclical parthenogenesis, heterogamy [ 14 ] [ 15 ] or heterogony [ 16 ] [ 17 ] ).
Reproduction (or procreation or breeding) is the biological process by which new individual organisms – "offspring" – are produced from their "parent" or parents. There are two forms of reproduction: asexual and sexual. In asexual reproduction, an organism can reproduce without the involvement of another organism.
Sexual reproduction is the most common life cycle in multicellular eukaryotes, such as animals, fungi and plants. [6] [7] Sexual reproduction also occurs in some unicellular eukaryotes. [2] [8] Sexual reproduction does not occur in prokaryotes, unicellular organisms without cell nuclei, such as bacteria and archaea.
Spinycheek crayfish (Orconectes limosus) can reproduce both sexually and by parthenogenesis. [20] The Louisiana red swamp crayfish (Procambarus clarkii), which normally reproduces sexually, has also been suggested to reproduce by parthenogenesis, [21] although no individuals of this species have been reared this way in the lab.