What is Difference Between Sexual And Asexual Reproduction?
Difference Between Sexual And Asexual Reproduction is that Reproduction consists in the ability to live beings to produce beings similar to those existing since the purpose of all species is to perpetuate themselves in space and time. Even so, we must distinguish between reproduction and multiplication, which is only an increase in the population, which does not have to happen in reproduction.
There are two types of reproduction: vegetative or asexual and sexual or generative. The asexual reproduction does not involve cell attachment and individuals develop it to give others identical to them. The sexual reproduction involves binding of special germ cells, gametes, possessing genetic variability due to meiosis.
Within the reproduction in plants, we will begin seeing asexual reproduction in plants.
Asexual reproduction of plants
There are two types of asexual reproduction in plants: vegetative and germ multiplication:
1. Vegetative multiplication: Ensures the perpetuation of individuals well adapted to that environment and evolutionarily effective. It is very common even on higher floors. There are two types: fragmentation and cell division that encompasses bipartition and budding.
The fragmentation is the fragmentation of parts of cells, thalli or shanks of individuals children arise. An example of fragmentation is cuttings. In bipartition, the stem cell is completely divided into two new daughter cells of equal size, typical of archaea and bacteria. In cell budding, the size of the daughter cell is initially smaller than that of the stem cell. By budding, the buds of the plants that give rise to new branches attached to the plant are generated.
2. By germs. Germs are asexual reproductive cells that directly develop the individual. There are several types: multicellular – the propagules – and generally unicellular – the spores.
There are areas where portions of the stem or stem of multicellular plants are particularly specialized to separate from the mother plant and spread, are the propagules (cell clusters), are very common in the lower plants. There are several types, the cyanobacterial hormogonia, potato tubers, garlic bulbs, stolons, rhizomes …
Tubers
They are thickened roots that facilitate underground propagation. An example is a potato.
Stolons
They are aerial stems that serve to propagate plants. An example is strawberries.
Rhizomes
They are underground stems with several buds that grow horizontally emitting roots and herbaceous shoots. They can grow indefinitely.
For example, the reed ( Phragmites australis )
Bulbs
They are short and conical stems with a large terminal bud surrounded by leaves that store reserve substances. In the armpits of these leaves renewal bulbs are formed. For example, it is the case of the tulip.
Spores are germ cells especially differentiated for asexual reproduction. They do not need fertilization to give rise to a complete individual. It is typical of pteridophytes (ferns), bryophytes (mosses) and fungi.
Spores
They are the most common form of asexual reproduction in plants, generally produce little variability, are dispersing agents and usually unicellulareas although there are spores with several cells or nuclei.
There are several types of spores according to the training conditions:
- Depending on the situation: exospores or conidia if they are formed outside by strangulation and endospores if they are formed inside a sporangium.
- Depending on the dispersal capacity: aplanósporas if they are immobile like pollen, many conidia, and zoospores or planósporas if they are mobile.
- Depending on the formation: mitospores or neutrósporas if they are diploid and meiospores, gonospores or “sexual” spores if they are haploid.
The spores also have special names such as: diplospores if they are diploid, haplósporas if they are haploid, if they are resistance spores they are called chlamydospores. If they occur in ascas they are ascospores, basidiospores if they occur in basidios . Heterosporous if they are generally different in size, microspores if they are small and masculine, megaspores if they are large and feminine.
The specialized structures where spores are produced are sporangia. They are unicellular (without cover) in algae and fungi; multicellular (with cover and archesporio which is the fertile tissue) from bryophytes to spermatophytes. Its nomenclature is the same as that of the spores, for example of meiospora meiosporangio.
Sexual reproduction
This type of reproduction is a much more complicated mechanism than asexual reproduction and it involves many factors.
Sexual reproduction involves the union of special germ cells, gametes, and is aimed at genetic variability by chromosomal recombination. This process is done in several stages. First, meiosis is performed to transform diploid cells into haploids that are gametes.Difference Between Sexual And Asexual Reproduction
Subsequently, the sing amid or union of haploid gametes occurs to form a diploid zygote, which involves plasmogamy (cytoplasmic junction) and a cariogamy or fertilization (nucleus junction).
The gametes are usually haploid, (n), and of opposite polarities (sexes), in addition, they occur in special structures, the gametangia.
There are several types of sexual reproduction:
- Isogamy: the union of gametes of equal shape and size but of different polarities.
- Anisogamy: Union of different gametes in shape and size and of opposite polarity.
- Oogamia: it is a special case of anisogamy but with a still female gamete and larger than the male.
Gametes, like spores, receive different names. The female gametes are called ovocell, oosphere, ovule; and the male antherozoid, anthozoans, sperm, sperm, sperm that can be immobile in some fungi.
Gametangios also receive special names, there are the same types as sporangia. The primitive gametangia are unicellular and can be covered by one or several cell walls.
The most evolved gametangia are multicellular with protective cover. In oogamy, the male gametangia are called antheridium and have a smaller size and filiform shape, the female one is called oogonium and has a larger size and spherical shape. From Briófitos onwards, the masculine is called anteidio and the feminine Argonia.
There are special cases of gametangiogamia in which fertilization is carried out by fusion of gametangia and subsequent union of gametes; of somatogamy in which no game tags are produced and somatic cells are coupled; and apomixis, sexual reproduction without fertilization, somatic cells play the role of germ. In this article, you can find more information about how to plant sperm are formed.Difference Between Sexual And Asexual Reproduction
The reproduction of angiosperm plants
The sexual reproduction of angiosperm plants is the most popular example. It is the reproduction of flowering plants. When a pollen grain reaches the flower’s pistil, pollination occurs. Upon entering the interior, the generation of germ cells or male gametes that fertilize the ovules in the gynecium is produced through the pollinator tube.
Once the ovules are fertilized, a process known as fertilization, the seeds are formed, and once they are formed, the gynecium becomes the fruit that we usually know as a result of the reproduction of the plants.
In fertilization, two haploid cells with different genetic material are joined, which join together forming an individual of a different genotype from the parents and for this reason, it is called sexual reproduction.
In summary, the stages of sexual reproduction in plants are as follows:
In summary, the stages of sexual reproduction in plants are as follows:
- Pollen formation in the stamens.
- Pollination: is when the pollen grain reaches the pistil. Pollination can occur in many different ways (wind, transported by animals, … you can see all types in this article on pollen dispersion )
- The male gametes reach the interior of the gynecium where the ovules are found through the pollinator tube.
- Fertilization: Singamia or union of female and male gametes occurs.
- Fertilization: the seeds are formed.
- The gynoecium becomes the fruit.
Origin and evolution of sexuality
It is thought that eukaryotes emerged about 600 M .A. from prokaryotes due to the invasion of new habitats and that these primitive eukaryotes are the protoctists.
The appearance of sexual reproduction occurred after the improvement of mitosis and the appearance of meiosis and the sexual cycle. The origin of mitosis could occur in protoctists and especially in dinoflagellates since their mitosis is “anomalous”, there is no mitotic spindle.
The origin of sexual reproduction may also have occurred in protoctists at the same time as mitosis because these organisms have both incomplete processes. It arose as a consequence of the adaptive advantage that it assumed since having chromosomal recombination is exploratory and innovative and facilitates the colonization of new habitats. In the reproduction of plants, this type occurs as we have already seen together with asexual reproduction.
If you want to expand more information about the sexual and asexual reproduction of plants or botany in general, we recommend the book Strasburger: Botany Treaty from which some of this information has been extracted. In addition, it is the classic and header book of any botany student.
You May Also Interested: