Reproduction or procreation or breeding is the biological process by which new individual organisms — "offspring" — are produced from their "parents". Reproduction is a fundamental feature of all known life ; each individual organism exists as the result of reproduction.
There are two forms of reproduction: In asexual reproduction, an organism can reproduce without the involvement of another organism. Asexual reproduction is not limited to single-celled organisms. The cloning of an organism is a form of asexual reproduction. By asexual reproduction, an organism creates a genetically
Reproduccion absexual or identical copy of itself. The evolution of sexual reproduction is a major puzzle for biologists.
Sexual reproduction typically requires the sexual interaction of two specialized organisms, called gameteswhich contain half the number of chromosomes of normal cells and are created by meiosiswith typically Reproduccion absexual male fertilizing a female of the same species to create a fertilized zygote.
This produces offspring organisms whose genetic characteristics are derived from those of the two parental organisms. Asexual reproduction is a process by which organisms create genetically similar or identical copies of themselves without the contribution of genetic material from another organism.
Bacteria divide asexually via binary fission ; viruses take control of host "Reproduccion absexual" to produce more viruses; Hydras invertebrates of the order Hydroidea and yeasts are able to reproduce Reproduccion absexual budding. These organisms often do not possess different sexes, and they are capable of "splitting" into two or more
Reproduccion absexual of themselves.
Most plants have the ability to reproduce asexually and the ant species Mycocepurus smithii is thought to reproduce entirely by asexual means. Some species that are capable of reproducing asexually, like hydrayeast See Mating of yeasts and jellyfishmay also reproduce sexually. For instance, most plants are capable of vegetative reproduction —reproduction without seeds or spores—but can also reproduce sexually.
Likewise, bacteria may exchange genetic information by conjugation. Other ways of asexual reproduction include parthenogenesisfragmentation and spore formation that involves only mitosis. Parthenogenesis is the growth and development of embryo or seed without fertilization by a male.
Parthenogenesis occurs naturally in some species, including lower plants where it is called apomixisinvertebrates e. It is sometimes also used to describe reproduction modes in hermaphroditic species which can self-fertilize. Sexual reproduction is a biological process that creates a new organism by combining the genetic material of two organisms in a process that starts with meiosisa specialized type of cell division.
Each of two parent organisms contributes Reproduccion absexual of the offspring's genetic makeup by creating haploid gametes. Most organisms form two different types of gametes. In these anisogamous species, the two sexes are referred to as male producing sperm or and female producing ova or megaspores.
In isogamous Reproduccion absexualthe gametes are similar or identical in form isogametesbut may have separable properties and then may be given other different names see isogamy.
For example, in the green alga, Chlamydomonas reinhardtiithere are so-called "plus" and "minus" gametes. A few types of organisms, such as many fungi and the ciliate Paramecium aurelia have more than two "sexes", called syngens.
Most animals including humans and plants reproduce sexually. Sexually reproducing organisms have different sets of genes for every trait called alleles. Offspring inherit one allele for each trait from each parent. Thus, offspring have a combination of the parents' Reproduccion absexual. It is that "the masking of deleterious alleles favors the evolution of a dominant diploid phase in organisms that alternate between haploid and diploid phases" where recombination occurs freely.
Bryophytes reproduce sexually, but the larger and commonly-seen organisms are haploid and produce gametes. The gametes fuse to form a zygote which develops into a sporangiumwhich in turn produces haploid spores.
The diploid stage is relatively small and short-lived compared to the haploid stage, i. The advantage of diploidy, heterosis, only exists in the diploid life generation. Bryophytes retain sexual reproduction despite the fact that the haploid stage does not benefit from heterosis. This may be an indication that the sexual reproduction has advantages other than heterosis, such as genetic recombination between members of the species, allowing the expression of a wider range of traits and thus making the population more able to survive environmental variation.
Reproduccion absexual the fertilization of the combination of gametes from two parents, generally the ovum from one individual with the spermatozoa of Reproduccion absexual.
In isogamous species, the two gametes will not be defined as either sperm or ovum. Self- fertilizationalso known as autogamy, occurs in hermaphroditic organisms where the Reproduccion absexual gametes fused in fertilization come from the same individual, e.
The term "autogamy" is sometimes substituted for autogamous pollination not necessarily leading to successful fertilization and describes self-pollination within the same Reproduccion absexual, distinguished from geitonogamous pollinationtransfer of pollen to a different flower on the same flowering plant or within a single monoecious Gymnosperm plant.
Mitosis and meiosis are types of cell division.
Mitosis occurs in somatic Reproduccion absexualwhile meiosis occurs in gametes. Mitosis The resultant number of cells in mitosis is twice the number of original cells. The number of chromosomes in the offspring cells is the same as that of the parent cell. Meiosis The resultant number of cells is four times the number of original cells. This results in cells with half the number of chromosomes present in the parent cell.
A diploid cell duplicates itself, then undergoes two divisions tetraploid to Reproduccion absexual to haploidin the process forming four haploid cells.
This process occurs in two phases, meiosis I and meiosis II. In recent decades, developmental biologists have been researching and developing techniques to facilitate same-sex reproduction. It is therefore concluded that most of the W-bearing PGC could not differentiate Reproduccion absexual spermatozoa because of restricted spermatogenesis.
There are a wide range of reproductive strategies employed by different species. Some animals, such as the human and northern gannetdo not reach sexual maturity for many years after birth and even then produce few offspring.
Others reproduce quickly; but, under normal circumstances, most offspring do not survive to adulthood.