Cell theory

From Free net encyclopedia

Cell theory is a scientific theory that is one of the foundations of biology. The generally accepted parts of cell theory include:

The cell is the fundamental unit of structure and function in living things.
All organisms are made up of one or more cells.
Cells arise from other cells through cellular division.
Cells carry genetic material passed to daughter cells during cellular division.
All cells are essentially the same in chemical composition.
Energy flow (metabolism and biochemistry) occurs within cells.

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cell theory

In 1838, the botanist Matthias Jakob Schleiden and Theodor Schwann, a physiologist discovered that both plant and animal cells had nuclei. From this realization, they surmised that all living things were composed of cells. In 1839, Schwann published 'Microscopic Investigations on the Accordance in the Structure and Growth of Plants and Animals', which contained the first statement of the cell theory.

Schwann and Schleiden's statement of the cell theory was:

Cells are the unit of structure, physiology, and organization in living things.
Cells are both a distinct entity and a building block in the construction of organisms.
Cells form by spontaneous generation.

When abiogenesis was later disproven, the third tenet was changed to state that all cells came from existing cells. The correct interpretation of cell formation by division was finally promoted by others and formally enunciated in 1858 in Rudolph Virchow's powerful dictum, "Omnis cellula e cellula"... "All cells only arise from pre-existing cells".

For a more detailed history visit: http://fig.cox.miami.edu/~cmallery/150/unity/cell.text.htm

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