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Cell theory

The discovery and introduction of the term "cell" belongs to R. Hooke. However, the scientist perceived it (the cell) as a void in the homogeneous (homogeneous) substance that constituted the plant. The animal cell was first described by Leuvenook, who discovered erythrocytes and spermatozoa. The instruments (microscopes) used by the researchers of the 17th and 18th centuries did not allow us to reliably establish any generality of the microscopic structure of the elements of the animal organs.

Despite the fact that the plant components were more accessible for study, the cellular theory was a disjointed and unsystematic knowledge. After Hooke researchers say that plant tissues have a specific structure, characterized by the presence in different parts of different microscopic elements. But there were no conclusions or generalizations from observations at that time.

In the 18th century microscopic studies did not yield any qualitatively new knowledge. Only with the beginning of the factory production of microscopes did the study continue. By the 30th years of the 19th century, the work of the leading botanists of that time made it possible to strengthen knowledge of the elementary structure of plants. From that moment the cell gets the status of an "elementary structure". Using the method of maceration (infusion), the assumption of the presence of common walls of microscopic particles is destroyed. Thus, scientists come to the conclusion that the cell is a closed structure. Moreover, it is endowed with some independence.

G. Mole and L. H. Treviranus reveal that plant structures in which no cellular structure is found are formed initially by the fusion of individual cells. The elementary system acquires the importance of a morphological and physiological component, in which an independent metabolism takes place.

The microscopic anatomy of the animal organism was actively studied by the Müller school and the Purkinje school. Thanks to their work, a huge amount of factual material was collected.

The cellular theory of the structure of organisms was directly formulated by Schwann (German zoologist, researcher) in 1839. Due to the fact that in his studies the zoologist was based on the works of the botanist Schleiden, the latter is rightly considered to be the co-author of Schwann.

Cell theory was a generalization of numerous data, based on the similarity of animals and elementary plant structures. The same mechanism of their formation was proved. Thus, the cellular theory of Schwann characterizes the cell as the functional and structural basis of a living being.

Subsequently, the researcher M. Badi applied this knowledge to the study of protozoa. K. Siebold definitively formulated (in 1845) a provision on the unicellular nature of protozoa.

Cell theory was, however, revised in the late 19th century. R. Virchow (German scientist) put forward a new assumption. Based on the new data, he concluded that the cell is formed only from the pre-existing cell. Virchow also put forward the hypothesis of a "cellular state". According to this assumption, the multicellular organism includes relatively independent units whose vital functions are carried out in close interrelation with each other.

Cellular theory has become a reflection of morphological unity throughout the entire organic nature. This, in turn, contributed to the development and strengthening of evolutionary teaching.

Modern cellular theory is based on three positions.

According to the first thesis, the elementary structure corresponds with the living nature of the whole planet. In other words, this proposition asserts that, regardless of the form of life, structural, genetic and functional development is provided only by the cell.

According to the second provision, the appearance of new elementary units occurs only on the basis of the division of pre-existing ones. In this case, all cells equally preserve biological information, apply information to perform their tasks on the basis of protein synthesis.

According to the third provision, the elementary structure corresponds to a multicellular organism, for which systemic organization and integrity are characteristic.

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