Cell theory is one of the most fundamental theories in biology. It has severe consequences in all fields related to biology. Matthias Schleiden and Theodor Schwann are recognized for developing the cell theory in 1839. However, there was a lot of research done over the previous decades which opened the way for them.
Timeline for Cell Theory
The timeline for cell theory is as follow:
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| Timeline for cell theory |
1625 - first microscope invented
Galileo Galilei, an Italian scientist, developed the first microscope.
1665 - discovery of cell
Robert Hooke discovered cell while studying the section of cork under his self-made microscope. He published his work in Micrographia. He observed small honeycomb-like compartments which he called a cell. He described a cell as a space bounded by a thick wall.
1670 - observation of living organisms
Anton van Leeuwenhoek observed living things (bacteria and protozoa) in a drop of pond water for the first time using single-lens microscopes. He named these organisms “animalcules,” meaning “miniature animals.”
1804 - cell is independent
Karl Rudolph along with J.H.F. proved that cells are independent with their separate cell walls.
1805 - living things madeup of cells
A German scientist, Lorenz Oken in this essay, 'Die Zeugung' argued that all living things are created from or consist of vesicles or cells.
1809 - no life without cell
Jean Baptist de Lamarck described “nobody can have a life if its constituent parts are not cellular tissue or are not formed by cellular tissue”.
1831 - discovery of nucleus
The presence of a nucleus in the cell by Robert Brown was reported. This discovery overwrites the idea of Hooke that a cell is a space. So, it was established that the cell is not space.
1838-1839 - cell theory
The German botanist Matthias Schleiden suggested that all plant tissues are composed of cells. A German zoologist, Theodor Schwann also established the idea that all animal tissues consist of cells. They both working independently came out with cell theory.
They discovered that a cell is made up of three basic parts i.e., nucleus, fluid surrounding the nucleus, and outer covering. They described that plant cell has an additional covering called the cell wall. They concluded that all living organisms are composed of cells and cellular products.
1845 - call basic unit of life
Carl Heinrich Braun reviewed the cell theory and called the cell the basic unit of life.
1855 - Omnis cellula e cellula
A German physician, Rudolph Virchow hypothesized that existing living cells divide to form new cells. As he said “Omnis cellula e cellula”.
1862 - Pasteur experiment
Louis Pasteur confirmed the idea of Rudolph Virchow by demonstrating that a new bacterial cell was formed from the existing bacterial cell.
1880 - basic origin of all living organisms
August Weismann explained that all living organisms have a common origin as they all have basic similarities in structure.
Video lesson on cell theory timeline
Cell theory 3 parts
The three parts of cell theory are:
- All organisms are made up of one or more cells
- All cells arise from preexisting cells
- Cell is the structural and functional unit of life
1. All organisms are made up of one or more cells
A cell is the unit of life. Cell organelles floating in the cytoplasm are wrapped by a cell membrane to form a compact structure of the cell. Cell stores all the necessary information for the survival of life. From unicellular to multicellular life, the cell is the common thing without which living organisms cannot come into existence.
2. All cells arise from preexisting cells
New cell originates by the division of the preexisting cell. No cell can generate spontaneously from organic or inorganic matter. DNA is replicated along with other cellular organelles and the cell is divided into two daughter cells.
3. Cell is the structural and functional unit of life
A cell contains organelles which perform the various function. There is a labor of division in multicellular organisms. For example, the nucleus stores DNA and control cellular functions, cell membrane control movement of molecules in and out of the cell and cytoplasm is the place for the cellular process. Without these organelles, the cell cannot survive and in turn, life cannot sustain. Cells combine to form different structures such as tissues, organs, and organ systems, thus, the cell is the structural unit of the living organism.
Video lesson on cell theory 3 parts
Conclusion
A cell is similar yet surprisingly versatile. A cell is the fundamental unit of the living organism, so cell theory is a very important concept in biology.
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