Meaning of cell theory

What is cell theory:

The cell theory postulates that all organisms are made up of cells, that the cell is the basic unit of life, and that all cells come from other cells.

The postulates of the cell theory were only possible thanks to the invention of the microscope by the Dutch merchant Zacharias Janssen in 1590. This innovation was modified by the English scientist Robert Hooke, creating in 1665 the microscope that allowed him to observe the first cells.

Robert Hooke (1635-1703) coined the term "cell" defining it as basic units of organisms, reaching that conclusion by observing only dead tissues, such as a cork.

Some years later, the Dutch merchant Anthony van Leeuwenhoek (1632-1723) improved Hooke's telescope and observed living cells for the first time, identifying microorganisms. Because of this discovery, we know him as the "father of microbiology."

The foundations of the cell theory are defined 200 years after the observation of the first cells. The first 2 postulates of the cell theory of Theodor Schwann and Matthias J. Scheiden respectively state:

  1. The cell is the basic unit of life
  2. All life is made up of cells

Postulates of cell theory

Modern cell theory lays its foundations on the 2 initial postulates of the Prussian biologist Theodor Schwann (1810-1882) and the German botanist Matthias J. Scheiden (1804-1881) during the 1830s:

First postulate

The cell is the basic unit of life

This first postulate of Theodor Schwann begins with the foundations of what we know as cell theory. This means that the cell is a structural unit, that is, that all organisms are made up of cells, the basic structure of life.

Second postulate

All life is made up of cells

The second postulate defined by the botanist Matthias Schleiden, speaks of the cell as a functional unit of organisms since they contain all the vital and indispensable processes for life.

In this sense, modern cell theory defines the cell as a reproductive unit, due to its ability to generate other cells through cell divisions such as mitosis and meiosis.

Third postulate

All cells come from other cells

This postulate indicates that every cell originates by division of another cell and therefore contains the necessary genetic information within themselves. That is why the cell is also recognized as a hereditary unit.

This postulate is by Robert Remak (1815-1865) but was wrongly attributed to Rudolf Virchow, later known for having plagiarized the studies on cells.

Importance of cell theory

The 3 basic postulates of cell theory were born between 1830 and 1855, a time when there was still a division in the scientific community about the origin of life. On one side were the abiogenists, who believed in spontaneous generation, and on the other side the biogenists, who claimed that life could only arise from another pre-existing life. This last group was formed when Anthony van Leeuwenhoek discovered microorganisms in 1668, but the theory of biogenesis would only be validated by the scientific community in 1887.

All the postulates of the cell theory indicate the cell as the unit of origin, being the basic unit of life, the only unit from which others can be born and necessarily starting from a pre-existing one.

Today, self-replicating molecules have been studied within our organisms that may have existed in the universe before the first cells were formed. There are still many theories that must be studied and that is why it is important that the cell theory continue with its investigations and observations.

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