- What is cell theory?
- What is the cell theory?
- History of cell theory
- Principles of cell theory
- Postulates of cell theory
We explain what cell theory is, its postulates and principles. Also, the history of its background and how it was verified.
What is cell theory?
Cell theory is one of the most important and central postulates in the field of biology modern. It states that absolutely all living beings are made up of cells. This includes all organisms of our planet.
This theory also describes the role of cells in history evolutionary of life on the planet. Based on this, he explains the main characteristics of the living creatures.
Cell theory forever revolutionized the way the human being understands life and organizes it. Consequently, he opened numerous fields of specialized knowledge and solving many of the questions about his body and that of the animals, which accompanied him since ancient times.
From its demonstration, this theory shed light on the origin of the life and about the reproduction. In addition, it allowed us to understand the dynamics and processes of what is now considered the most basic physiological unit of biology: the cell.
What is the cell theory?
Cell theory, as we said before, focused the efforts of biology on the cell as the minimal structure of life. Understand that all forms of life are cell-based, that is, all tissues of the plants, animals and mushrooms they can be broken down into individual cells, although unique and differentiated.
However, animal cells, the plant cells or the cells of the single-celled organisms they are very different from each other. Furthermore, this perspective allowed us to understand the gigantic cellular diversity that exists, not only between primitive and single-celled life forms, but even within our own bodies.
On the other hand, all the studies regarding the basic processes of life, such as being born, growing, reproducing and dying, can not only be traced to the cellular level of the organism, but also occur, in turn, in each of cells of the body.
History of cell theory
The cell theory has its antecedents in a long history of studies on life that began in the ancient civilizations. However, it was only with the invention of the microscope that plant cells could be observed in the 17th century, as did the Italian biologist Marcello Malpighi (1628-1694).
It was then that the debate began regarding what exactly those structures were. Later english Robert hooke (1635-1703) he baptized them as cellulae, from the Latin "cell", from its observations of cork cuts.
Later, the Dutch Anton van Leeuwenhoek (1632-1723), considered the father of the microbiology, began to use various microscopes of his own authorship to observe the quality of the fabrics he traded. But then he turned to the observation of other substances.
Thus, van Leeuwenhoek was the first to observe bacteria, protozoa and the sperm themselves. In this way he also gave the first blows to the prevailing theory regarding the spontaneous generation of life.
Other later scientists made significant contributions to the emergence of the cell theory. For example, the Frenchman Xavier Bichat (1771-1802) was the first to define a tissue as a set of cells with similar shape and function.
On the other hand, the Germans Theodor Schwann (1810-1882) and Matthias Jackob Schleiden (1804-1881), formulated the first principle of the cell theory: all living beings are made up of cells and their secretions. Later, the German Rudolf Virchow (1821-1902), was the first to demonstrate cellular bipartition, that is, that cells come from other cells.
Despite these discoveries, the cell theory was debated throughout the entire 19th century. Finally, the Frenchman Louis Pasteur (1822-1895) fully verified this theory with his experiments to show that life is not spontaneously generated.
Principles of cell theory
The principles that govern cell theory are roughly the same as those of modern biology. This implies the distinction between living and inert: living matter is capable of metabolizing (nourishing) and self-perpetuating (reproducing), for which it must have the necessary structures, present inside the cell.
Another important principle is that of inheritance: the transmission of biological information to descendants allows the persistence of a species. This process also depends on important cellular structures, such as the cell nucleus, where is contained the DNA of the species whole.
Ultimately, cells come together in multicellular organisms to form tissues, which are larger, homogeneous structures of cells of the same type. In doing so, they obey important diversification criteria, such as those that separate nerve, muscle, liver cells, etc.
Postulates of cell theory
The cell theory can be reduced to three fundamental postulates:
- All living things are made up of cells. Therefore, these are the minimum functional unit of life, in its different levels of structural complexity. One cell is enough to constitute an organism (unicellular), but many cells can organize themselves in colonies or in the same single organism (multicellular), diversifying their functions and reaching a very high margin of interdependence.
- The vital functions of organisms take place within cells. Through biochemical processes, and are controlled by substances that cells secrete. Each cell operates as a system single open, which exchanges matter Y Energy with your environment in a controlled way. Furthermore, in each cell of an organism the same vital functions occur as in the entire organism: birth, growth, reproduction, death.
- All the cells that exist come from previous cells. By cell division or by formation from stem cells. The oldest and most primitive cells in the world are the prokaryotes (without cell nucleus).