Reproduction is a property inherent in all living things.organisms. It is this that ensures the continuity of the generations of all modern species. In this article we will get acquainted with this concept and its main characteristics.
By reproduction we mean the ability of everythinglive to reproduce their own kind. In other words, multiply. Depending on what features of the structure has an organism and at what level of the organization is located, several types of this process are singled out.
The main of them are two: sexual and asexual.The first type of reproduction occurs with the participation of specialized cells, which are called gametes. Progeny in this case appears as a result of the fusion of their genetic material.
Asexual reproduction occurs without the participation of gametes. Its result is identical individuals, which are an exact copy of the maternal organism.
In bacteria, unicellular animals and plantsreproduction is a division by mitosis. At the same time, the number of children is twice as large as the parent. The new cells are genetically identical to the parent cells.
Everyone knows how the reproduction takes placepotatoes. This is a process that is carried out with the help of specialized formations - tubers. These escapes have buds. Sprouting, they give rise to a new organism. This can occur with the help of bulbs, rhizomes, individual parts of the shoot. Separation from the whole organism of its multicellular part is called vegetative reproduction. It is not unique to plants. For example, earthworms can restore missing parts of the body. This kind of vegetative reproduction is called fragmentation.
During asexual reproduction of freshwater hydraon her body first there is a slight protrusion. With the passage of time, it increases in size, acquires the features of an adult organism, separates and passes to independent existence. Such a method of asexual reproduction is called budding. This process can be observed visually and in some mushrooms. For example, when the yeast dough "approaches".
A sexless process is also the formation of a dispute.These are specialized cells that are formed in mosses, mosses, horsetails and fungi. Spores have protective shells and are capable of withstanding unfavorable conditions: high and low temperatures, salinity, and pressure.
Seed reproduction is an example of the sexual processin plants. These generative organs consist of an embryo, reserve substances necessary for its development, and a protective peel. The gymnosperm seeds mature on scales of cones. Flowering plants have a number of advantages. These include double fertilization and the presence of fruits that protect the seeds from unfavorable conditions.
Reproduction of a person is also a result offertilization of gametes. They mature in specialized organs, which are called glands. Male germ cells, or spermatozoa - in the testes. Female, or ovum - in the ovaries. The process of fertilization in humans occurs in the female body. This fertilization is called internal. Although a different type of this process is known in nature. Thus, female fish and amphibians spawn in water, where males water her with seminal fluid. This fertilization is called external.
The main advantage of sexual reproduction is the recombination of genetic material. This allows the species to adapt to new conditions of life.
Sexual reproduction always involves participationmale and female gametes. But in nature this is not always possible. Adaptation to this situation is parthenogenesis. This is the form of the sexual process, during which a new organism develops from an egg that has not been fertilized.
There is another form of the sexual process -conjugation. It is observed in prokaryotes and infusoria. Naturally, these organisms do not have gametes. With conjugation between two daughter cells, a cytoplasmic bridge is formed, along which genetic information is exchanged between them.
So reproduction or reproduction is a process of reproducing oneself. This property of organisms ensures the continuity of generations and the continuity of life.
