What is the cell theory?
The cell theory, also known as the cell doctrine. It is the most basic principle underlying the field of cells and biology. Modern cell theory states 6 different rules. These include:
- The cell is the structural and functional unit of all living things.
- All organisms are composed of one or more cells.
- Most humans, animals and plants have more than one cell. These organisms are known as multicellular organisms. However, some types of bacteria consist of only one cell. These types of organisms are called unicellular organisms.
- New cells come from pre-existing cells; lifeforms today have descended in unbroken continuity from the first primitive cells that arose on earth more than 3.5 billion years ago.
- Hereditary information passes from parent cell to child cell.
- All cells have the same basic chemical structure.
- Energy flow occurs within cells
What is the history behind cells and the cell theory?
More than 330 years ago there was no knowledge of cells. This is because they were too small for the naked eye. The discovery of the microscope made it possible to examine cells and even study them in detail. Robert Brown discovered the nucleus, the engine that makes a cell function.
Years later in 1838, a German botanist, Matthias Jakob Schleiden was the first to discover that cells are the smallest unit or, the "building blocks" of all plants. In the following year, another German botanist, Theodor Schwann stated that cells are the smallest units of animals too. These statements ended the belief that plants and animals have differences in structure. Both of their discoveries led to the creation of the ‘Cell Theory’ which states that cells are the basic units of all living organisms (plants and animals). In 1855, Rudolf Virchow, a German physiologist stated that new cells come from already existing cells. In the following years, scientists also discovered that the body units in charge of reproduction are also cells. As years went by, the 6 principles of the cell theory formed. |
Matthias Jakob Schleiden (left) and Theodor Schwann (right)
Rudolf Virchow
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