A Sexual Reproduction

1466 Words Nov 14th, 2012 6 Pages
ASEXUAL REPRODUCTION

Asexual reproduction is a mode of reproduction by which offspring arise from a single parent, and inherit the genes of that parent only; it is reproduction which does not involve meiosis, ploidy reduction, or fertilization. The offspring will be exact genetic copies of the parent. A more stringent definition is agamogenesis which is reproduction without the fusion of gametes. Asexual reproduction is the primary form of reproduction for single-celled organisms such as the archaea,bacteria, and protists. Many plants and fungi reproduce asexually as well.
While all prokaryotes reproduce asexually (without the formation and fusion of gametes), mechanisms for lateral gene transfer such as conjugation, transformation and
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Plants that reproduce vegetatively may form a clonal colony, where all the individuals are clones, and the clones may cover a large area.

SPORE FORMATION

Many multicellular organisms form spores during their biological life cycle in a process called sporogenesis. Exceptions are animals and some protists, who undergo gametic meiosisimmediately followed by fertilization. Plants and many algae on the other hand undergo sporic meiosis where meiosis leads to the formation of haploid spores rather than gametes.

FRAGMENTATION

Fragmentation is a form of asexual reproduction where a new organism grows from a fragment of the parent. Each fragment develops into a mature, fully grown individual. Fragmentation is seen in many organisms such as animals (some annelid worms, turbellarians and sea stars), fungi, and plants. Some plants have specialized structures for reproduction via fragmentation, such asgemmae in liverworts.

AGAMOGENESIS

Agamogenesis is any form of reproduction that does not involve a male gamete. Examples are parthenogenesis and apomixis. Parthenogenesis is a form of agamogenesis in which an unfertilized egg develops into a new individual. Parthenogenesis occurs naturally in many plants, invertebrates (e.g. water fleas, rotifers, aphids, stick insects, some ants, bees and parasitic wasps), and vertebrates (e.g. some reptiles, amphibians, fish, very rarely birds).

REGENERATION

In biology, regeneration is the process of renewal,