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All living organisms, with the exception of viruses, are made up of cells. Cells, most often represented by microscopic formations, have all the most important vital properties: self-regulation, self-reproduction, unity of structure and function, historical development, etc. The cells constantly undergo metabolic processes and energy conversion.

The science that studies the structure and functioning of cells is called cytology (from the Greek. Kytos - cell + logos - science). The development and development of cytology was largely determined by the improvement of the microscopic technique, since cells are difficult to study with the naked eye.

In 1665, an English naturalist R. Hooke first reported the existence of cells. He examined under a microscope improved by him thin sections of the cork and found small empty pores and cells, which he called cells. Strictly speaking, R. Hook observed dead cells in the cork section, devoid of any living contents that filled them. Exploring under a microscope various parts of other plants, in particular carrots, burdock, fern, he discovered the same structure plan as that of cork.

In 1677, M. Malpighi reported on the cellular structure of all the plants he studied. A prominent scientist of the XVII century. A. van Leeuwenhuk, examining a drop of water under a microscope, discovered the simplest unicellular organisms. For a long time, the cell's main structural component was recognized as its membrane.

After the beginning of the XIX century. there was a technical improvement in the quality of the lenses, quickly increased attention to research using a microscope. In 1825, the Czech scientist J. Purkinje showed that there is a gelatinous substance inside the cell, later called cytoplasm. English botanist R. Brown described the cell nucleus. The German botanist M. Schleiden in 1837 concluded that all plant cells contain nuclei.

In 1839, the German zoologist T. Schwann, summarizing his own experimental data and the results of other scientists, formulated a concept currently known as cell theory. According to cell theory: 1) the cell is the main element of life; 2) any organisms consist of one or many cells. Indeed, despite the enormous diversity of living beings, differing in size (see table), shape, habitat, method of movement, energy supply, etc., the basis of their morphofunctional organization are the cells. R. Virkhov in 1855 added to these two postulates a fundamental position: “Omnis cellula e cellulae” - “Every cell from a cell”. In other words, the third position of the cell theory states that all cells are formed only as a result of the division of other cells.
The current content of cell theory can be summarized as follows: the main structural and functional unit of living organisms is the cell.

Cellular theory is the most important achievement of natural science. She played a prominent role in the development of not only biology and medicine, but also many other branches of the science of man.

Subsequent successes of cytology and cytogenetics were associated with the development and improvement of research methods. The central role of the nucleus in cell division was proved after the invention of the method of staining cytological preparations by V. Fleming in 1879. The improvement of light microscopes made it possible to obtain new information about the structure of the cell and some of its structures. However, the resolution of the light microscope is limited by the ability of the human eye, which can perceive two points separately at a distance of not less than 0.1 mm. With this resolution, some cellular structures are not visible, and the study of others is significantly more difficult.

A major step forward was an invention in the 30s. electron microscope V. Zvorykin and phase contrast microscope F. Zernike. An increase of 100 thousand times, which provides an electron microscope, allows you to study the smallest details of cellular organelles. Modern advances in cytology and cytogenetics are associated with the development of chemical, physical methods and technologies (from X-ray analysis to computer databases).

In multicellular organisms, each cell is specialized to perform, as a rule, one of the functions necessary to ensure the vital activity of the organism as a whole.

Depending on the function they perform, cells can vary significantly in terms of size, shape, location in various tissues and organs of the body, as well as other external and internal characteristics.

We indicate the main types of specialization of cells of a multicellular organism. It:

? perception of external and internal stimuli;

? coordination of all functions (cells of the nervous and endocrine systems);

? movement and support;

? protection of the body (cells of integumentary tissues and the immune system);

? obtaining nutrients or their synthesis;

? transfer of nutrients, biologically active substances, gases, etc .;

? removal of decay products; reproduction.
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    As a result of a huge number of microscopic studies in the XVII — XVIII centuries. accumulated a wealth of factual material about the structure of plant and animal organisms. However, the metaphysical way of thinking inherent in feudalism, which prevailed at that time, did not contribute to theoretical generalizations of these facts. Considering nature as an accidental accumulation of objects created
  2. Cell cycle Cell cycle regulating molecules open the door to diagnosing and killing cancer cells
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  3. What is the difference between sickle cell anemia and sickle cell anomaly?
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  4. Hepatocellular failure
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  6. Sickle Cell Hemoglobinopathies
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  12. Topic: Cellular Immunity
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