Life is both wonderful and majestic. Yet for all of its majesty, all organisms are composed of the fundamental unit of life, the cell. The cell is the simpliest unit of matter that is alive. From the unicellular bacteria to multicellular animals, the cell is one of the basic organizer of living organisms.
The cell was first discovered by Robert Hooke in 1665, which can be found to be described in his book Micrographia. He discoveres a multitude of tiny pores that he named "cells". Anton Van Leeuwenhoek is another scientist who saw these cells with the use of microscope. He found motile objects and stated that motility is a quality of life. He later named these "animalcules", which include protozoa and other unicellular organisms, like bacteria.
Cell theory is one of the basic principles of biology. In 1838, Matthias Jakob Schleiden suggested that every structural part of a plant was made opun cell or the result of cells. He also suggested that cells were made by crystallization process either within other cells or from the outside. In 1839, Theodor Schwaan stated that along with the plants, animals are composed of cells or the product of cells in their structure.
This was a major advancement in the field of bioligy since little was known about animal structure up to this point compared to plants. From these conclusions about plants and animals, cell theory were postulated:
1. All living organisms are composed of one or more cells.
2. The cell is the most basic unit of life. And lastly
3. All Cells arise only from pre-existing cells.