Theory of Cell
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Theory of Cell
Structure of Cell of Class 11
In the early 19th century, several facts about plant and animal cells came forth which led the German Botanist Matthias Schleiden and German Zoologist Theodor Schwann (1839) to establish the cell theory.
Schwann coined the word “metabolism” for all chemical processes occuring in the cell and called cells “the unit of life”.
Cell theory was modified by Rudolf Virchow (1855) in his famous aphorism. “Omnis cellulae e cellulae’ i.e. all cells arise from pre-existing cells, which established cell division as the central phenomenon in the reproduction of organisms.
Nageli and Virchow modified the cell theory of Schleiden and Schwann and now this modern version of cell theory states that :
(i) Cells are the morphological and physiological units of all living organisms.
(ii) The properties of a given organism depend on its individual cells.
(iii) Cells originate from other cells and continuity is maintained through genetic material.
(iv) Smallest unit of life is the cell.
