We explain what sexual and asexual reproduction are and what their characteristics are. Also, why they are so important and examples.

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Each form of reproduction has different laws of genetic inheritance.

What are sexual and asexual reproduction?

Sexual and asexual reproduction are the two general forms of reproduction known in all living things. Each one implies a set of specific methods of reproduction, typical of each species, and they differ in their genetic basis, that is, in the laws of genetic inheritance that govern them.

A) Yes, asexual reproduction, the more primitive of both, implies the generation of new individuals from the same and unique progenitor. This means that the parent duplicates its genetic material to create identical replicas of itself.

However, sexual reproduction requires two individuals combining half of their respective genetic codes. In this way, a unique fusion of cells is achieved that produces a new individual, with its own unique genetic material. This method requires the production of specialized cells or reproductive cells, called gametes. Unlike the rest of the cells, they possess half of the genetic load of the individual. The unique mission of these cells is to combine with another of the opposite sex to generate a new individual.

See also: Microorganisms

Importance of reproduction

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Reproduction helps perpetuate the species.

reproduction is one of the main tasks of organizations. All life forms have one way or another of producing new young individuals. This way the species is perpetuated. can be interpreted as the way life beats death: individuals perish, but the species persists over time.

There is also, in the case of multicellular and complex living beings, the need to repair damaged tissue and replenish old cells. This need is also satisfied through reproduction, but on a smaller scale: that of the cells of the body.

asexual reproduction in animals

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Some echinoderms can reproduce by fragmentation.

The animals that resort to asexual reproduction to form new individuals, generally, are those unicellular and primitive, called protozoa. It is enough for them to reach a certain degree of maturity or growth to start a phase of cell division that can be:

  • Binary fission. Although this process is more common in prokaryotes, living beings are much simpler still.
  • Mitosis. in more complex organisms.
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Mitosis is the division of eukaryotic cells. in two genetically identical offspring. This is achieved through the replication of the cell nucleus and the DNA it contains. Once it’s duplicated, it moves away from each other inside the cell, duplicating the organelles.

Once both the cell and the organelles are found in duplicate, the cytoplasm is strangleduntil completely separating the two new descendants.

In addition to being used by simple organisms for reproduction, this mechanism takes place in somatic cells (endowed with complete genetic material) from animals, in cases where tissues need to be augmented with identical cells. This occurs during the growth of the body or during the repair of damaged tissues.

Though most animals do not use this mechanism for the reproduction of individuals (since they reproduce sexually), there are exceptions. They are animals endowed with embryonic totipotency, that is, their cells can not only multiply, but also differentiate and rebuild the tissues necessary to create a whole organism.

The sponges, echinoderms, annelids, and some lizards They are animals capable of reproducing an entire individual from a single cell by various methods:

  • Bipartition. Division in two of an individual.
  • Fragmentation. Construction of whole individuals from their fragments.
  • Parthenogenesis. Creation of an identical individual from unfertilized female gametes.

asexual reproduction in plants

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Plants generate entire and genetically identical individuals.

Plants can reproduce both sexually and asexually, depending on the conditions. Asexual reproduction occurs, as in animals, for the construction of new fabrics necessary for growth, the regeneration of damaged tissues or the creation of new structures.

But, in addition, plants can reproduce asexually generating from whole and identical individuals genetically to the parent. For this, they do not require flowering and pollination, but the starting of stems, rhizomes, shoots, mitospores (spores generated by mitosis) or propagules. A lot of plants They reproduce like this under certain conditions. and resort to sexual reproduction when it is necessary to increase the genetic variety.

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sexual reproduction in animals

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Sexual reproduction grants genetic variants in the same litter.

Animals have sexual reproduction to generate new organisms. Via the combination of one’s own DNA with that of other individuals within the same species more genetic variations are achieved.

This process is useful for the species because prevents the accumulation of genetic mutations or defects during DNA replication. Even if an animal gives birth to three or four offspring in one litter, each one will have slightly different genetic information.

sexual reproduction requires the creation of gametes, usually sperm (male) and ova (female). Each one has half the genetic load of the individual (n, haploid) and they are specialized cells for reproduction.

A sperm and an egg must meet and produce a zygote (fertilized egg). Depending on the species, this encounter occurs in the environment or within the body of the female. In this second case, in some species the female then lays eggs (oviparous) from which the young will later hatch, or she gives birth to live young (viviparous).

sexual reproduction in plants

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Bees collaborate with the sexual reproduction of plants.

When Plants produce flowers, seeds, and fruits.They reproduce sexually. To do this, they require the exchange of pollen loaded with genetic material between plants, due to the action of the wind or animals that are attracted by the smell of their flowers (such as bees or hummingbirds) and carry them from one’s stomata to the pistils. of other.

Once fertilized, the flowers produce seeds and these seeds are thrown into the environment. If the conditions are right, these seeds then generate new individuals with their own genome, if the conditions are right.

Sometimes the plants produce fruits that surround the seeds. This gives the seeds a better chance of spreading away from the parent, either by wind or by animals that eat the fruit and carry the seed away.

Examples of sexual reproduction

Sexual reproduction is the most abundant of multicellular living beings. Examples of this are:

  • Pollination of tree flowers.
  • The internal fertilization of mammals that later give birth to their young.
  • The external fertilization of certain fish, whose females deposit the eggs so that the male fertilizes them separately.

Examples of asexual reproduction

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Bacteria reproduce by bipartition.

Asexual reproduction is common in the primitive world:

  • Bacteria reproduce by dividing once they have reached a certain size in the appropriate media.
  • Plants can also do it, through shoots, rhizomes, segments or grafts.
  • Organisms that generate spores and endospores, such as fungi.
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Importance of asexual reproduction

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Species that do not compete with others thrive quickly.

Asexual reproduction is the simplest of reproductions. It is key in the colonization of habitats by life forms because where one individual thrives there are soon dozens, then hundreds and even thousands of the same individuals. By not competing with other species, they thrive quickly.

Importance of sexual reproduction

sexual reproduction represents an evolutionary leap forward with respect to the asexual, since it allows a genetic combinatorics. Firstly, this protects the offspring from sharing the same genes and therefore the same mutations or DNA replication defects.

On the other hand, sexual reproduction gives the species greater diversity, since each descendant has a somewhat different genome. This diversity favors adaptation. For this reason, this mode of reproduction was key to the emergence of complex life and multicellular beings, endowed as they are with highly specialized cells.

human reproduction

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Both sperm and egg provide genetic material.

human reproduction It’s always sexual, that is, it requires the production of eggs (by the woman) and sperm (by the man). Both come into contact in the woman’s womb, usually through intercourse or by artificial insemination methods.

After 9 months of cell division and of formation of a unique individual, this one is given birth by the woman and thus a new member is added to the species. Genetically it is similar to both parents, but its DNA is unique and unrepeatable.

There is the possibility, of course, of asexually reproducing a human being, through techniques such as cloning. But such experiments are ethically frowned upon. However, the human being, like any other animal, relies on the asexual reproduction of its cells, for tissue restitution or growth.

References:

  • “Sexual reproduction” on Wikipedia.
  • “Asexual reproduction” on Wikipedia.
  • “Sexual and asexual reproduction” in the CCH Academic Portal of the National Autonomous University of Mexico.
  • “Reproduction: asexual vs. sexuality” in cK-12.
  • “Asexual and sexual reproduction: Mitosis and Meiosis” in O Courses at the National University of Distance Education.
  • “Sexual and Asexual Reproduction” on ABC Color.

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