What is eukaryote: definition of the concept, features of the structure

What is eukaryote? The answer to this question lies in the peculiarities of the structure of cells of various types. The nuances of their organization we will consider in our article.

Features of the structure of cells

Cells of living organisms are classified according to different signs. One of them is the organization of hereditary material encased in DNA molecules. Eukaryotes are organisms in which cells the formed nucleus is located. It is a two-membrane organelle containing genetic material. In prokaryotes this structure is absent. Such organisms include all kinds of bacteria and archaea.

The structure of prokaryotic cells

The absence of a nucleus does not mean that prokaryotic organisms do not have a hereditary material. It is also encoded in a sequence of nucleotides. However, the genetic information is located not in the formed nucleus, but is represented by a single circular DNA molecule. It's called a plasmid. Such a molecule is attached to the inner surface of the plasma membrane. Cells of this type are also devoid of a number of definite organelles. Prokaryotic organisms are characterized by primitiveness, small size and low level of organization.

What is eukaryote?

To this numerous group of organisms are all representatives of plants, animals and fungi. Viruses are non-cellular forms of life, so this classification is not considered.

The surface apparatus of prokaryotic cells is represented by the plasma membrane, and the internal content by the cytoplasm. It is an internal semi-fluid medium that performs a supporting function, integrating all the structures into a single whole. Prokaryotic cells are also characterized by the presence of a certain number of organoids. This is the Golgi complex, endoplasmic network, plastids, lysosomes. Some believe that eukaryotes are organisms in the cells of which there are no mitochondria. But this is not so. These organelles in eukaryotic cells serve as the site for the formation of ATP-energy molecules in the cell.

Eukaryotes: examples of organisms

Eukaryotes are the three kingdoms of living nature. However, in spite of common features, their cells have significant differences. For example, vegetable are characterized by the maintenance of specialized organelles of chloroplasts. It is in them that a complex photochemical process of the transformation of inorganic substances into glucose and oxygen takes place. Animals do not have such structures. They are able to absorb only ready-made nutrients. These structures differ also in the structure of the surface apparatus. In the animal cells above the plasma membrane is glycocalyx. It is a viscous surface layer, consisting of proteins, lipids and carbohydrates. For plants, the cell wall is characteristic . It is located above the plasma membrane. The cell wall is formed by complex carbohydrates cellulose and pectin, which give it strength and rigidity.

What is eukaryote, which is represented by a group of mushrooms? The cells of these amazing organisms combine the features of the structure of both plants and animals. The composition of their cell wall includes carbohydrates cellulose and chitin. However, their cytoplasm does not contain chloroplasts, therefore they, like animal cells, are capable only of a heterotrophic method of nutrition.

Progressive features of the structure of eukaryotes

Why are all eukaryotes the organisms that have reached a high level of development and spread across the planet? First of all, due to the high level of specialization of their organelles. The ring DNA molecule, which is contained in bacterial cells, provides the easiest way to reproduce them - dividing the cell in two. As a result of this process, exact genetic copies of daughter cells are formed. Reproduction of this type, of course, ensures the continuity of generations and ensures a sufficiently rapid reproduction of such cells. However, the emergence of new features in the course of division in two and speech can not go. And this means that these organisms will not be able to adapt to changing conditions. For eukaryotic cells, the sexual process is characteristic. In its course, there is an exchange of genetic information and its recombination. As a result, individuals with new, often useful signs appear, which are fixed in their genotype and can be transmitted from generation to generation. This is the manifestation of hereditary variability, which is the basis of evolution.

So, in this article we have examined what a eukaryote is. This concept means an organism whose cells contain a nucleus. To this group of organisms are all representatives of the plant and animal world, as well as fungi. The nucleus is a permanent cellular structure that provides storage and transmission of hereditary information to organisms encoded in a sequence of nucleotides of DNA molecules.