Reproduction is a property inherent in all living organisms. It is it that ensures the continuity of generations of all modern species. In our article we will get acquainted with this concept and its main characteristics.
Reproduction is ...
By reproduction we understand the ability of all living things to reproduce their own kind. In other words, to multiply. Depending on what structural features the organism has and at what level of organization it is, several types of this process are distinguished.
The main of them are two: sexual and asexual. The first type of reproduction occurs with the participation of specialized cells called gametes. The offspring at the same time appears as a result of the merger of their genetic material.
Asexual reproduction occurs without the participation of gametes. Its result is identical individuals, which are an exact copy of the mother's body.
Forms of asexual reproduction
In bacteria, unicellular animals and plants, reproduction is division by mitosis. At the same time, the number of daughter individuals is twice as large as the maternal ones. New cells are always genetically identical to parent cells.
Everyone knows how to reproduce potatoes. This is a process that is carried out with the help of specialized entities - tubers. These modifications of the shoot have kidneys. Germinating, 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 propagation. It is characteristic not only for plants. For example, earthworms can repair missing parts of the body. This kind of vegetative propagation is called fragmentation.
During asexual reproduction of freshwater hydra, a slight protrusion first appears on her body. Over time, it grows in size, acquires the features of an adult organism, separates and transfers to independent existence. This method of asexual reproduction is called budding. This process can also be observed visually in some mushrooms. For example, when yeast dough “fits”.
The asexual process is the formation of spores. These are specialized cells that are formed in mosses, plunds, horsetails and fungi. Spores have protective shells and are able to tolerate adverse conditions: high and low temperature, salinity, and pressure.
Sexual process
Seed reproduction is an example of the reproductive process in plants. These generative organs consist of the embryo, the reserve substances necessary for its development, and the protective peel. In gymnosperms, the seeds ripen on the scales of the cones. Flowering plants have several advantages. These include double fertilization and the presence of fruits that protect the seeds from adverse conditions.
Human reproduction is also the result of fertilization of gametes. They ripen in specialized organs called glands. Male germ cells, or sperm cells - in the testes. Female, or ovules - in the ovaries. The process of fertilization in humans occurs in the female body. Such fertilization is called internal. Although another type of this process is known in nature. So, females of fish and amphibians spawn in water, where males water it with seminal fluid. Such fertilization is called external.
The main advantage of sexual reproduction is the recombination of genetic material. This allows the mind to adapt to new living conditions.
Parthenogenesis and conjugation
Sexual reproduction always involves the participation of male and female gametes. But in nature, this is not always possible. Adaptation to this situation is parthenogenesis. This is a 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 ciliates. Naturally, these organisms do not have gametes. During conjugation between two daughter cells, a cytoplasmic bridge is formed through which genetic information is exchanged between them.
So, reproduction, or reproduction is the process of reproducing oneself. This property of organisms ensures the continuity of generations and the continuity of life.