Who is the creator of the cell theory? Cell theory. Cell theory video

) supplemented it with the most important position (every cell comes from another cell).

Schleiden and Schwann, summarizing the existing knowledge about the cell, proved that the cell is the basic unit of any organism. Animal, plant and bacterial cells have a similar structure. Later, these conclusions became the basis for proving the unity of organisms. T. Schwann and M. Schleiden introduced into science the fundamental concept of the cell: there is no life outside cells. The cell theory was supplemented and edited every time.

Provisions of the Schleiden-Schwann cell theory

1. All animals and plants are made up of cells.
2. Plants and animals grow and develop through the emergence of new cells.
3. A cell is the smallest unit of living things, and a whole organism is a collection of cells.

Basic provisions of modern cell theory

1. The cell is the elementary unit of life; outside the cell there is no life.
2. A cell is a single system; it includes many naturally interconnected elements, representing an integral formation consisting of conjugated functional units - organelles.
3. The cells of all organisms are homologous.
4. A cell comes into being only by dividing the mother cell, after doubling its genetic material.
5. A multicellular organism is a complex system of many cells united and integrated into systems of tissues and organs connected to each other.
6. The cells of multicellular organisms are totipotent.

Additional provisions of the cell theory

To bring the cell theory into more complete compliance with the data of modern cell biology, the list of its provisions is often supplemented and expanded. In many sources, these additional provisions differ; their set is quite arbitrary.

1. Prokaryotic and eukaryotic cells are systems of different levels of complexity and are not completely homologous to each other (see below).
2. The basis of cell division and reproduction of organisms is the copying of hereditary information - nucleic acid molecules (“each molecule of a molecule”). The concept of genetic continuity applies not only to the cell as a whole, but also to some of its smaller components - mitochondria, chloroplasts, genes and chromosomes.
3. A multicellular organism is a new system, a complex ensemble of many cells, united and integrated in a system of tissues and organs, connected to each other through chemical factors, humoral and nervous (molecular regulation).
4. Multicellular cells are totipotent, that is, they have the genetic potential of all cells of a given organism, are equivalent in genetic information, but differ from each other in the different expression (function) of various genes, which leads to their morphological and functional diversity - to differentiation.

Story

17th century

Link and Moldnhower established the presence of independent walls in plant cells. It turns out that the cell is a certain morphologically separate structure. In 1831, Mole proved that even seemingly non-cellular plant structures, such as aquifers, develop from cells.

Meyen in “Phytotomy” (1830) describes plant cells that “are either solitary, so that each cell is a special individual, as is found in algae and fungi, or, forming more highly organized plants, they are combined into more or less significant masses." Meyen emphasizes the independence of metabolism of each cell.

In 1831, Robert Brown describes the nucleus and suggests that it is a permanent component of the plant cell.

Purkinje School

In 1801, Vigia introduced the concept of animal tissue, but he isolated tissue based on anatomical dissection and did not use a microscope. The development of ideas about the microscopic structure of animal tissues is associated primarily with the research of Purkinje, who founded his school in Breslau.

Purkinje and his students (especially G. Valentin should be highlighted) revealed in the first and most general form the microscopic structure of the tissues and organs of mammals (including humans). Purkinje and Valentin compared individual plant cells with individual microscopic tissue structures of animals, which Purkinje most often called “grains” (for some animal structures his school used the term “cell”).

In 1837, Purkinje gave a series of talks in Prague. In them, he reported on his observations on the structure of the gastric glands, nervous system, etc. The table attached to his report gave clear images of some cells of animal tissues. Nevertheless, Purkinje was unable to establish the homology of plant cells and animal cells:

• firstly, by grains he understood either cells or cell nuclei;
• secondly, the term “cell” was then understood literally as “a space bounded by walls.”

Purkinje conducted the comparison of plant cells and animal “grains” in terms of analogy, not homology of these structures (understanding the terms “analogy” and “homology” in the modern sense).

Müller's school and Schwann's work

The second school where the microscopic structure of animal tissues was studied was the laboratory of Johannes Müller in Berlin. Müller studied the microscopic structure of the dorsal string (notochord); his student Henle published a study on the intestinal epithelium, in which he described its various types and their cellular structure.

Theodor Schwann's classic research was carried out here, laying the foundation for the cell theory. Schwann's work was strongly influenced by the school of Purkinje and Henle. Schwann found the correct principle for comparing plant cells and elementary microscopic structures of animals. Schwann was able to establish homology and prove the correspondence in the structure and growth of the elementary microscopic structures of plants and animals.

The significance of the nucleus in a Schwann cell was prompted by the research of Matthias Schleiden, who published his work “Materials on Phytogenesis” in 1838. Therefore, Schleiden is often called the co-author of the cell theory. The basic idea of ​​cellular theory - the correspondence of plant cells and the elementary structures of animals - was alien to Schleiden. He formulated the theory of new cell formation from a structureless substance, according to which, first, a nucleolus condenses from the smallest granularity, and around it a nucleus is formed, which is the cell maker (cytoblast). However, this theory was based on incorrect facts.

In 1838, Schwann published 3 preliminary reports, and in 1839 his classic work “Microscopic studies on the correspondence in the structure and growth of animals and plants” appeared, the very title of which expresses the main idea of ​​cellular theory:

• In the first part of the book, he examines the structure of the notochord and cartilage, showing that their elementary structures - cells - develop in the same way. He further proves that the microscopic structures of other tissues and organs of the animal body are also cells, quite comparable to the cells of cartilage and notochord.
• The second part of the book compares plant cells and animal cells and shows their correspondence.
• In the third part, theoretical positions are developed and the principles of cell theory are formulated. It was Schwann's research that formalized the cell theory and proved (at the level of knowledge of that time) the unity of the elementary structure of animals and plants. Schwann's main mistake was the opinion he expressed, following Schleiden, about the possibility of the emergence of cells from structureless non-cellular matter.

Development of cell theory in the second half of the 19th century

Since the 1840s of the 19th century, the study of the cell has become the focus of attention throughout biology and has been rapidly developing, becoming an independent branch of science - cytology.

For the further development of cell theory, its extension to protists (protozoa), which were recognized as free-living cells, was essential (Siebold, 1848).

At this time, the idea of ​​the composition of the cell changes. The secondary importance of the cell membrane, which was previously recognized as the most essential part of the cell, is clarified, and the importance of protoplasm (cytoplasm) and the cell nucleus is brought to the fore (Mol, Cohn, L. S. Tsenkovsky, Leydig, Huxley), which is reflected in the definition of a cell given by M. Schulze in 1861:

A cell is a lump of protoplasm with a nucleus contained inside.

In 1861, Brücko put forward a theory about the complex structure of the cell, which he defines as an “elementary organism,” and further elucidated the theory of cell formation from a structureless substance (cytoblastema), developed by Schleiden and Schwann. It was discovered that the method of formation of new cells is cell division, which was first studied by Mohl on filamentous algae. The studies of Negeli and N.I. Zhele played a major role in refuting the theory of cytoblastema using botanical material.

Tissue cell division in animals was discovered in 1841 by Remak. It turned out that the fragmentation of blastomeres is a series of successive divisions (Bishtuf, N.A. Kölliker). The idea of ​​the universal spread of cell division as a way of forming new cells is enshrined by R. Virchow in the form of an aphorism:

"Omnis cellula ex cellula."
Every cell from a cell.

In the development of cell theory in the 19th century, contradictions arose sharply, reflecting the dual nature of cellular theory, which developed within the framework of a mechanistic view of nature. Already in Schwann there is an attempt to consider the organism as a sum of cells. This tendency receives special development in Virchow’s “Cellular Pathology” (1858).

Virchow’s works had a controversial impact on the development of cellular science:

• He extended the cell theory to the field of pathology, which contributed to the recognition of the universality of cellular theory. Virchow's works consolidated the rejection of the theory of cytoblastema by Schleiden and Schwann and drew attention to the protoplasm and nucleus, recognized as the most essential parts of the cell.
• Virchow directed the development of cell theory along the path of a purely mechanistic interpretation of the organism.
• Virchow elevated cells to the level of an independent being, as a result of which the organism was considered not as a whole, but simply as a sum of cells.

XX century

Since the second half of the 19th century, cell theory has acquired an increasingly metaphysical character, reinforced by Verworn’s “Cellular Physiology,” which considered any physiological process occurring in the body as a simple sum of the physiological manifestations of individual cells. At the end of this line of development of cell theory, the mechanistic theory of the “cellular state” appeared, including Haeckel as a proponent. According to this theory, the body is compared to the state, and its cells are compared to citizens. Such a theory contradicted the principle of the integrity of the organism.

The mechanistic direction in the development of cell theory was subjected to severe criticism. In 1860, I.M. Sechenov criticized Virchow’s idea of ​​the cell. Later, the cell theory was criticized by other authors. The most serious and fundamental objections were made by Hertwig, A. G. Gurvich (1904), M. Heidenhain (1907), Dobell (1911). The Czech histologist Studnicka (1929, 1934) made extensive criticism of the cellular theory.

In the 1930s, Soviet biologist O. B. Lepeshinskaya, based on her research data, put forward a “new cell theory” as opposed to “Vierchowianism.” It was based on the idea that in ontogenesis, cells can develop from some non-cellular living substance. A critical verification of the facts laid down by O. B. Lepeshinskaya and her adherents as the basis for the theory she put forward did not confirm the data on the development of cell nuclei from nuclear-free “living matter”.

Modern cell theory

Modern cellular theory proceeds from the fact that cellular structure is the most important form of existence of life, inherent in all living organisms, except viruses. The improvement of cellular structure was the main direction of evolutionary development in both plants and animals, and the cellular structure is firmly retained in most modern organisms.

At the same time, the dogmatic and methodologically incorrect provisions of the cell theory must be re-evaluated:

• Cellular structure is the main, but not the only form of existence of life. Viruses can be considered non-cellular life forms. True, they show signs of life (metabolism, ability to reproduce, etc.) only inside cells; outside cells, the virus is a complex chemical substance. According to most scientists, in their origin, viruses are associated with the cell, they are part of its genetic material, “wild” genes.
• It turned out that there are two types of cells - prokaryotic (cells of bacteria and archaebacteria), which do not have a nucleus delimited by membranes, and eukaryotic (cells of plants, animals, fungi and protists), which have a nucleus surrounded by a double membrane with nuclear pores. There are many other differences between prokaryotic and eukaryotic cells. Most prokaryotes do not have internal membrane organelles, and most eukaryotes have mitochondria and chloroplasts. According to the theory of symbiogenesis, these semi-autonomous organelles are descendants of bacterial cells. Thus, a eukaryotic cell is a system of a higher level of organization; it cannot be considered entirely homologous to a bacterial cell (a bacterial cell is homologous to one mitochondria of a human cell). The homology of all cells, thus, has been reduced to the presence of a closed outer membrane made of a double layer of phospholipids (in archaebacteria it has a different chemical composition than in other groups of organisms), ribosomes and chromosomes - hereditary material in the form of DNA molecules forming a complex with proteins . This, of course, does not negate the common origin of all cells, which is confirmed by the commonality of their chemical composition.
• The cellular theory considered the organism as a sum of cells, and the life manifestations of the organism were dissolved in the sum of the life manifestations of its constituent cells. This ignored the integrity of the organism; the laws of the whole were replaced by the sum of the parts.
• Considering the cell to be a universal structural element, the cell theory considered tissue cells and gametes, protists and blastomeres as completely homologous structures. The applicability of the concept of a cell to protists is a controversial issue in cellular theory in the sense that many complex multinucleated protist cells can be considered as supracellular structures. In tissue cells, germ cells, and protists, a general cellular organization is manifested, expressed in the morphological separation of karyoplasm in the form of a nucleus, however, these structures cannot be considered qualitatively equivalent, taking all their specific features beyond the concept of “cell”. In particular, gametes of animals or plants are not just cells of a multicellular organism, but a special haploid generation of their life cycle, possessing genetic, morphological, and sometimes environmental characteristics and subject to the independent action of natural selection. At the same time, almost all eukaryotic cells undoubtedly have a common origin and a set of homologous structures - cytoskeletal elements, eukaryotic-type ribosomes, etc.
• The dogmatic cell theory ignored the specificity of non-cellular structures in the body or even recognized them, as Virchow did, as non-living. In fact, in the body, in addition to cells, there are multinuclear supracellular structures (syncytia, symplasts) and nuclear-free intercellular substance, which has the ability to metabolize and is therefore alive. To establish the specificity of their life manifestations and their significance for the body is the task of modern cytology. At the same time, both multinuclear structures and extracellular substance appear only from cells. Syncytia and symplasts of multicellular organisms are the product of the fusion of parent cells, and the extracellular substance is the product of their secretion, that is, it is formed as a result of cell metabolism.
• The problem of the part and the whole was resolved metaphysically by the orthodox cell theory: all attention was transferred to the parts of the organism - cells or “elementary organisms”.

The integrity of the organism is the result of natural, material relationships that are completely accessible to research and discovery. The cells of a multicellular organism are not individuals capable of existing independently (the so-called cell cultures outside the body are artificially created biological systems). As a rule, only those multicellular cells that give rise to new individuals (gametes, zygotes or spores) and can be considered as separate organisms are capable of independent existence. A cell cannot be separated from its environment (as, indeed, any living systems). Focusing all attention on individual cells inevitably leads to unification and a mechanistic understanding of the organism as a sum of parts.

Almost 400 years passed from the moment the cells were discovered until the modern position of the cell theory was formulated. The cell was first examined in 1665 by a naturalist from England. Having noticed cellular structures on a thin section of cork, he gave them the name cells.

With his primitive microscope, Hooke could not yet examine all the features, but as optical instruments improved and techniques for staining preparations emerged, scientists became increasingly immersed in the world of subtle cytological structures.

How did the cell theory come about?

A landmark discovery that influenced the further course of research and the current position of cell theory was made in the 30s of the 19th century. The Scot R. Brown, studying a plant leaf using a light microscope, discovered similar rounded compactions in plant cells, which he later called nuclei.

From this moment on, an important feature appeared for comparing the structural units of different organisms with each other, which became the basis for conclusions about the unity of the origin of living things. It is not for nothing that even the modern position of cell theory contains a reference to this conclusion.

The question of the origin of cells was raised in 1838 by the German botanist Matthias Schleiden. While massively studying plant material, he noted that the presence of nuclei is mandatory in all living plant tissues.

His compatriot zoologist Theodor Schwann made the same conclusions regarding animal tissues. After studying Schleiden's work and comparing many plant and animal cells, he came to the conclusion: despite their diversity, they all have a common feature - a formed nucleus.

Cell theory of Schwann and Schleiden

Having put together the available facts about the cell, T. Schwann and M. Schleiden put forward the main postulate. It was that all organisms (plants and animals) consist of cells that are similar in structure.

In 1858, another addition to cell theory was made. proved that the body grows by increasing the number of cells by dividing the original maternal ones. This seems obvious to us, but for those times his discovery was very advanced and modern.

At that time, the current position of Schwann’s cell theory in textbooks was formulated as follows:

1. All tissues of living organisms have a cellular structure.
2. Animal and plant cells are formed in the same way (cell division) and have a similar structure.
3. The body consists of groups of cells, each of them is capable of independent life.

Having become one of the most important discoveries of the 19th century, cell theory laid the foundation for the idea of ​​the unity of origin and commonality of evolutionary development of living organisms.

Further development of cytological knowledge

Improvement of research methods and equipment has allowed scientists to significantly deepen their knowledge of the structure and functioning of cells:

• the connection between the structure and function of both individual organelles and cells as a whole has been proven (specialization of cytostructures);
• each cell individually demonstrates all the properties inherent in living organisms (grows, reproduces, exchanges matter and energy with the environment, is mobile to one degree or another, adapts to changes, etc.);
• organelles cannot individually exhibit such properties;
• animals, fungi, and plants have organelles that are identical in structure and function;
• All cells in the body are interconnected and work harmoniously, performing complex tasks.

Thanks to new discoveries, the provisions of the theory of Schwann and Schleiden were refined and supplemented. The modern scientific world uses the expanded postulates of the fundamental theory in biology.

In the literature you can find a different number of postulates of modern cell theory; the most complete version contains five points:

1. The cell is the smallest (elementary) living system, the basis for the structure, reproduction, development and vital activity of organisms. Non-cellular structures cannot be called living.
2. Cells appear solely by dividing existing ones.
3. The chemical composition and structure of the structural units of all living organisms are similar.
4. A multicellular organism develops and grows through the division of one/several original cells.
5. The similar cellular structure of the organisms inhabiting the Earth indicates a single source of their origin.

The original and modern provisions of the cell theory have many similarities. In-depth and expanded postulates reflect the current level of knowledge on the structure, life and interaction of cells.

In parallel with descriptive work, the cell theory was also formed. Already in 1809 The German natural philosopher L. Oken put forward a hypothesis of the cellular structure and development of organisms. These ideas were developed in Russia by P.F. Goryaninov, professor at the Medical-Surgical Academy of St. Petersburg. IN 1837 He wrote: “The entire organic kingdom is represented by bodies of cellular structure.” Goryaninov was the first to connect the problem of the origin of life with the origin of the cell.

Historically important, although practically incorrect, were the ideas of the German botanist M. Schleiden about the formation of new cells. IN 1838 He formulated the theory of cytogenesis (from the Greek cytos - cell and genesis - origin), according to which new cells are formed in old ones.

Based on the work of M. Schleiden, German biologist T. Schwann conducted a comparative study of animal and plant tissues. This allowed him to create 1839 d. cell theory, the main provisions of which are still valid. Thanks to this, T. Schwann is considered the founder of this theory, according to which all organisms have a cellular structure, and animal and plant cells have a fundamental similarity in structure and formation. The third position of Schwann's cell theory postulated that the activity of a multicellular organism is the sum of the vital activity of its individual cells.

In 1859 German pathologist R. Virchow made a significant change in cell theory regarding the formation of new cells. In contrast to the views of Schleiden and Schwann, R. Virchow argued that cells arise only through reproduction (division). It is he who owns the famous formulation " omnis cellula e cellula" (" every cell is from a cell"). Thus, Virchow can be considered one of the co-authors of the cellular theory. The subsequent development of biology confirmed the validity of the cellular theory, including bacteria in it. Even the discovery of viruses - non-cellular life forms - did not lead to a revision of the theory. It turned out that viruses are of cellular origin and were formed repeatedly during evolution from certain components of cells.

Basic provisions.

Currently, the main provisions of cell theory can be formulated in four theses.

1. All living organisms, excluding viruses, consist of cells and their metabolic products.This thesis reflects the unity of the cellular origin of all organisms and emphasizes the importance of non-cellular components, such as blood plasma, cerebrospinal fluid, and the extracellular matrix of connective tissues.

2. The cells of all living organisms have a fundamental similarity in their structure and basic metabolism, i.e. all cells are homologous (from the Greek homos - equal, identical and logos - concept).This thesis also reflects the unity of origin of all living organisms from a cellular ancestor - the protocell (see § 10). Any cell consists of three universal subsystems: the surface apparatus, the cytoplasm and the nuclear apparatus. The energy metabolism of all cells is based on the oxygen-free breakdown of carbohydrates - glycolysis. The vital activity of all cells is based on three universal processes: DNA synthesis, RNA synthesis and protein synthesis.

3. Each cell is formed only by dividing an existing cell.This position postulates the impossibility of spontaneous generation of cells in the conditions that developed after their origin and evolution. Since protobionts and many protocells were heterotrophs, they used organic substances in their metabolism. By doing this, they reduced the possibility of re-emergence of protobionts to zero. After the emergence of photosynthesis, an ozone screen appeared in the atmosphere, which sharply reduced the flow of high-energy short-wave ultraviolet rays to the Earth.

4. The activity of a multicellular organism consists of the activity of its cells and the results of their interactions.This thesis emphasizes that a multicellular organism is not a sum of cells, but a collection of interacting cells, i.e. system (from the Greek system - a whole made up of parts; connection). In it, the activity of each cell depends on the functioning of not only neighboring, but also cells distant from it. In particular, red blood cells supply oxygen to all cells of the body, secretory cells, secrete hormones, neurons form chains and networks.

Discovery and Exploration cells became possible thanks to the invention of the microscope and the improvement of microscopic research methods.

The Englishman Robert Hooke was the first in 1665 to observe the division of cork oak bark tissue into cells (cells) using magnifying lenses. Although it turned out that he did not discover cells (in the proper sense of the term), but only the outer shells of plant cells. Later, the world of single-celled organisms was discovered by A. Leeuwenhoek. He was the first to see animal cells (erythrocytes). Later, animal cells were described by F. Fontana, but these studies at that time did not lead to the concept of the universality of cellular structure, because there was no clear idea of ​​what a cell is.

R. Hooke believed that cells are voids or pores between plant fibers. Later, M. Malpighi, N. Grew and F. Fontana, observing plant objects under a microscope, confirmed R. Hooke’s data, calling the cells “bubbles”. A. Leeuwenhoek made a significant contribution to the development of microscopic studies of plant and animal organisms. He published the data of his observations in the book “Secrets of Nature”.

The illustrations in this book clearly demonstrate the cellular structures of plant and animal organisms. However, A. Levenguk did not represent the described morphological structures as cellular formations. His research was random and not systematic. G. Link, G. Travenarius and K. Rudolf at the beginning of the 19th century showed with their research that cells are not voids, but independent formations limited by walls. It was found that the cells have contents that I Purkinje called protoplasm. R. Brown described the nucleus as a permanent part of cells.

T. Schwann analyzed literature data on the cellular structure of plants and animals, comparing them with his own research and published the results in his work. In it, T. Schwann showed that cells are the elementary living structural units of plant and animal organisms. They have a common structural plan and are formed in a single way. These theses became the basis of the cell theory.

Researchers have been accumulating observations of the structure of unicellular and multicellular organisms for a long time before formulating the principles of CT. It was during this period that various optical research methods were more developed and improved.

Cells are divided into nuclear (eukaryotic) and non-nuclear (prokaryotic). Animal organisms are built from eukaryotic cells. Only mammalian red blood cells (erythrocytes) do not have nuclei. They lose them in the process of their development.

The definition of a cell has changed depending on the knowledge of their structure and function.

Definition 1

According to modern data, cell is a structurally ordered system of biopolymers limited by an active shell, which form the nucleus and cytoplasm, participate in a single set of metabolic processes and ensure the maintenance and reproduction of the system as a whole.

Cell theory is a generalized idea of ​​the structure of the cell as a living unit, the reproduction of cells and their role in the formation of multicellular organisms.

Progress in the study of cells is associated with the development of microscopy in the $19th century. At that time, the idea of ​​the structure of the cell changed: not the cell membrane, but its contents - protoplasm - was taken as the basis of the cell. At the same time, the nucleus was discovered as a permanent element of the cell.

Information about the fine structure and development of tissues and cells made it possible to make a generalization. Such a generalization was made in 1839 by the German biologist T. Schwann in the form of the cell theory he formulated. He argued that the cells of both animals and plants are fundamentally similar. These ideas were developed and generalized by the German pathologist R. Virchow. He put forward an important point, which was that cells arise only from cells through reproduction.

Basic principles of cell theory

T. Schwann in 1839, in his work “Microscopic studies on the correspondence in the structure and growth of animals and plants,” he formulated the basic principles of the cell theory (later they were refined and supplemented more than once.

Cell theory contains the following provisions:

• cell is the basic elementary unit of the structure, development and functioning of all living organisms, the smallest unit of living things;
• the cells of all organisms are homologous (similar) (homologous) in their chemical structure, the main manifestations of life processes and metabolism;
• cells reproduce by division - a new cell is formed as a result of the division of the original (mother) cell;
• in complex multicellular organisms, cells specialize in the functions they perform and form tissues; organs are built from tissues, closely interconnected by intercellular, humoral and nervous forms of regulation.

The intensive development of cytology in the $19th and $20th centuries confirmed the basic principles of CT and enriched it with new data on the structure and functions of the cell. During this period, certain incorrect theses of T. Schwann’s cell theory were discarded, namely, that an individual cell of a multicellular organism can function independently, that a multicellular organism is a simple collection of cells, and the development of a cell occurs from a non-cellular “blastema”.

In its modern form, cell theory includes the following basic provisions:

1. A cell is the smallest unit of living things, which has all the properties that meet the definition of “living”. These are metabolism and energy, movement, growth, irritability, adaptation, variability, reproduction, aging and death.
2. The cells of different organisms have a common structural plan, which is due to the similarity of general functions aimed at maintaining the life of the cells themselves and their reproduction. The variety of cell shapes is the result of the specificity of the functions they perform.
3. Cells reproduce as a result of the division of the original cell with the previous reproduction of its genetic material.
4. Cells are parts of an entire organism, their development, structural features and functions depend on the whole organism, which is a consequence of interaction in the functional systems of tissues, organs, apparatuses and organ systems.

Note 1

The cell theory, which corresponds to the modern level of knowledge in biology, in many respects is fundamentally different from the ideas about the cell not only at the beginning of the 19th century, when T. Schwann formulated it for the first time, but even in the middle of the 20th century. In our time, this is a system of scientific views that has acquired the form of theories, laws and principles.

The basic principles of CT have retained their significance to this day, although over more than 150 years new information has been obtained about the structure, vital activity and development of cells.

The importance of cell theory

The significance of the cell theory in the development of science is that thanks to it it became clear that the cell is the most important component of all organisms, their main “building” component. Since the development of each organism begins with one cell (zygote), the cell is also the embryonic basis of multicellular organisms.

The creation of the cell theory became one of the decisive proofs of the unity of all living nature, the most important event in biological science.

Cell theory contributed to the development of embryology, histology and physiology. It provided the basis for the materialistic concept of life, for explaining the evolutionary relationship of organisms, for the concept of the essence of ontogenesis.

The basic principles of CT are still relevant today, although over a period of more than 100 years, natural scientists have received new information about the structure, development and vital activity of the cell.

The cell is the basis of all processes in the body: both biochemical and physiological, since it is at the cellular level that all these processes occur. Thanks to the cellular theory, it became possible to come to the conclusion about the similarity in the chemical composition of all cells and once again be convinced of the unity of the entire organic world.

Cell theory is one of the most important biological generalizations, according to which all organisms have a cellular structure.

Note 2

The cellular theory, together with the law of energy transformation and the evolutionary theory of Charles Darwin, is one of the three greatest discoveries of natural science of the 19th century.

Cell theory radically influenced the development of biology. She proved the unity of living nature and showed the structural unit of this unity, which is the cell.

The creation of the cell theory became the most important event in biology, one of the decisive proofs of the unity of all living nature. Cell theory had a significant and decisive influence on the development of biology and served as the main foundation for the development of such disciplines as embryology, histology and physiology. It provided the basis for explaining the family relationships of organisms and for the concept of the mechanism of individual development.

Cell theory is perhaps the most important generalization of modern biology and is a system of principles and provisions. It is the scientific background for many biological disciplines that study the structure and functioning of living beings. Cell theory reveals the mechanisms of growth, development and reproduction of organisms.

Question 1. Who developed the cell theory?

The cell theory was formulated in the mid-19th century. German scientists Theodor Schwann and Matthias Schleiden. They summarized the results of many discoveries known at that time. The main theoretical conclusions, called the cell theory, were outlined by T. Schwann in his book “Microscopic studies on the correspondence in the structure and growth of animals and plants” (1839). The main idea of ​​the book is that plant and animal tissues are made up of cells. A cell is a structural unit of living organisms.

Question 2. Why was the cell called a cell?

Dutch scientist Robert Hooke, using his magnifying device design, observed a thin section of cork. He was amazed that the cork turned out to be built from cells that resembled a honeycomb. Hooke called these cells cells.

Question 3. What properties do all cells of living organisms share?

Cells have all the characteristics of life. They are capable of growth, reproduction, metabolism and energy conversion, have heredity and variability, and respond to external stimuli.

2.1. Basic principles of cell theory

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