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 Asexual and sexual reproduction compare prices of reproduction.
There are two forms of reproduction: In asexual Asexual and sexual reproduction compare prices, 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 By asexual reproduction, an organism creates a genetically similar 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 Asexual and sexual reproduction compare prices chromosomes of normal cells and are created by meiosiswith typically Asexual and sexual reproduction compare prices 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 cells to produce more viruses; Hydras invertebrates of the order Hydroidea and yeasts are able to reproduce by budding.
These organisms often do not possess different sexes, and they are capable of "splitting" themselves into two or more copies of themselves. Most plants have the ability to reproduce asexually Asexual and sexual reproduction compare prices 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
Asexual and sexual reproduction compare prices 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 half 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 microspores and female producing ova or megaspores. In isogamous speciesthe gametes are similar or identical in form isogametesbut may have separable properties and then may be Asexual and sexual reproduction compare prices 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
Asexual and sexual reproduction compare prices 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' genes. It is believed 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.
Allogamy is the fertilization of the combination of gametes from two parents, generally the ovum from one individual with the spermatozoa of another.
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 two gametes fused in fertilization come from the same individual,
The term "autogamy" is sometimes substituted for autogamous pollination not necessarily leading to successful fertilization and describes self-pollination within the same flower, 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 cellswhile meiosis occurs in gametes. Mitosis The resultant number of cells in mitosis is twice the number of Asexual and sexual reproduction compare prices Asexual and sexual reproduction compare prices. The number of chromosomes in 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 diploid to haploidin the Asexual and sexual reproduction compare prices 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 into 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. For example, a rabbit mature after 8 months can produce 10—30 offspring per year, and a fruit fly mature after 10—14 days can produce up to offspring per year. These two main strategies are known as K-selection few offspring and r-selection many offspring. Which strategy is favoured by evolution depends on a variety of circumstances.
Animals with few offspring can devote more resources to the nurturing and protection of each individual offspring, thus reducing the need for many offspring. On the other hand, animals with many offspring may devote fewer resources to each individual offspring; for these Asexual and sexual reproduction compare prices of animals it is common for many offspring to die soon after birth, but enough individuals typically survive to maintain the population.
Asexual and sexual reproduction compare prices organisms such as honey
Asexual and sexual reproduction compare prices and fruit flies retain sperm in a process called sperm storage thereby increasing the duration of their fertility. Organisms that reproduce through asexual reproduction tend to grow in number exponentially. However, because they rely mutation for variations in their DNA, all members of the species have similar vulnerabilities.
Organisms that reproduce sexually yield a smaller number of offspring, but the large amount of variation in their genes makes them less susceptible to disease.
Many organisms can reproduce sexually as well as asexually. Aphidsslime moldssea anemonessome species of starfish by fragmentationand many plants are examples. When environmental factors are favorable, asexual reproduction is employed to exploit suitable conditions for survival such as an abundant food supply, adequate shelter, favorable climate, disease, optimum pH or a proper mix of other lifestyle requirements.
Populations of these organisms increase exponentially via asexual reproductive strategies to take full advantage of the rich supply resources. When food sources have been depleted, the climate becomes hostile, or individual survival is jeopardized by some other adverse change in living conditions, these organisms switch to sexual forms of reproduction. Sexual reproduction ensures a mixing of the gene pool of the species. The variations found in offspring of sexual reproduction allow some individuals to be better suited for survival and provide a mechanism for selective adaptation occur.
The meiosis stage of the sexual cycle also allows especially effective repair of DNA damages see Meiosis and Bernstein et al. Thus, seeds, spores, eggs, pupae, cysts or other "over-wintering" stages of sexual reproduction ensure the survival during unfavorable times and the organism can "wait out" adverse situations until a swing back to suitability occurs.
The existence of life without reproduction is the subject of some speculation. The biological study of how the origin of life produced reproducing organisms from non-reproducing elements is called abiogenesis.
Whether or there were several independent abiogenetic events, biologists believe that the last universal ancestor to all present life on Earth
Asexual and sexual reproduction compare prices about 3. Scientists have speculated about the possibility of creating life non-reproductively in the laboratory.
Several scientists have succeeded in producing simple viruses from entirely non-living materials. Being nothing more than a bit of RNA or DNA in a protein capsule, they have no metabolism and can only replicate with the assistance of a hijacked cell 's metabolic machinery.
The production of a truly living organism e. A synthetic genome has been transferred into an existing bacterium where it replaced the native DNA, resulting in the artificial production of a new M. There is some debate within the scientific community over whether this cell can be considered completely synthetic  on the grounds that the chemically synthesized genome was an almost 1: The Craig Venter Institute maintains the term bacterial cell" but they also clarify " They also propose to stretch the boundaries between life and machines until the two overlap to yield "truly programmable organisms".
Sexual reproduction has many drawbacks, since it requires far more energy than asexual reproduction and diverts the organisms from other pursuits, and there is some argument about why so many species use it.
Asexual and sexual reproduction compare prices used lottery tickets as an analogy in one explanation for the widespread use of sexual reproduction. Sexual reproduction, he argued, was like purchasing fewer tickets but with a greater variety of numbers and therefore a greater chance of success.
The point of this analogy is that since asexual reproduction does not produce genetic variations, there is little ability to quickly adapt to a changing environment. The lottery principle is less accepted these days because of evidence that asexual reproduction is more prevalent in unstable environments, the opposite of what it predicts. From Wikipedia, the free encyclopedia.
For other uses, see Asexual and sexual reproduction compare prices disambiguation. Modes of reproduction and Life history theory. Archived from the original on November 15, Mating Types in Paramecium Aurelia: Proceedings of the American Philosophical Society, Vol. Available online Asexual and sexual reproduction compare prices intechopen.
The Wall Street Journal. Retrieved April 13,