What is a eukaryote? The answer to this question lies in the structural features of cells of various types. We will consider the nuances of their organization in our article.
Features of cell structure
Cells of living organisms are classified according to different criteria. One of them is the organization of hereditary material contained in DNA molecules. Eukaryotes are organisms whose cells contain a formed nucleus. It is a two-membrane organelle containing genetic material. Prokaryotes do not have this structure. These organisms include all types of bacteria and archaea.
Structure of prokaryotic cells
The absence of a nucleus does not mean that prokaryotic organisms do not have hereditary material. It is also encoded in the nucleotide sequence. However, 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 also lack a number of certain organelles. prokaryotic organismscharacterized by primitiveness, small size and low level of organization.
What is a eukaryote?
This large group of organisms includes all representatives of plants, animals and fungi. Viruses are non-cellular life forms and therefore are not considered in this classification.
The surface apparatus of prokaryotic cells is represented by the plasma membrane, and the internal contents - by the cytoplasm. This is an internal semi-liquid medium that performs a supporting function, unites all structures into a single whole. Prokaryotic cells are also characterized by the presence of a certain number of organelles. These are the Golgi complex, endoplasmic network, plastids, lysosomes. Some believe that eukaryotes are organisms whose cells lack mitochondria. But that's not the case at all. These organelles in eukaryotic cells serve as the site for the formation of ATP molecules, the energy carrier in the cell.
Eukaryotes: examples of organisms
Eukaryotes are the three kingdoms of wildlife. However, despite the similarities, their cells have significant differences. For example, plants are characterized by the content of specialized chloroplast organelles. It is in them that a complex photochemical process of converting inorganic substances into glucose and oxygen takes place. Animal cells do not have such structures. They are able to absorb only ready-made nutrients. These structures differ in the structure of the surfacedevice. In animal cells, the glycocalyx is located above the plasma membrane. It is a viscous surface layer consisting of proteins, lipids and carbohydrates. Plants have a cell wall. It is located above the plasma membrane. The cell wall is made up of the complex carbohydrates cellulose and pectin, which give it strength and rigidity.
What is a eukaryote, which is represented by a group of fungi? The cells of these amazing organisms combine the structural features of both plants and animals. The composition of their cell wall includes carbohydrates cellulose and chitin. However, their cytoplasm does not contain chloroplasts, so they, like animal cells, are only capable of heterotrophic nutrition.
Progressive structural features of eukaryotes
Why are all eukaryotes organisms that have reached a high level of development and distribution around the planet? First of all, due to the high level of specialization of their organelles. The circular DNA molecule found in bacterial cells provides the easiest way for them to reproduce - by 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 fairly rapid reproduction of such cells. However, the appearance of new signs in the course of dividing in two is out of the question. And this means that these organisms will not be able to adapt to changing conditions. Eukaryotic cells are characterized by the sexual process. ATits course is the exchange of genetic information and its recombination. As a result, individuals are born with new, often useful traits that are fixed in their genotype and can be passed on from generation to generation. This is the manifestation of hereditary variability, which is the basis of evolution.
So, in our article we looked at what a eukaryote is. This concept means an organism whose cells contain a nucleus. This group of organisms includes 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 of organisms, encoded in the sequence of nucleotides of DNA molecules.
