CELL THEORY

'Cell theory' is a scientific theory that is one of the foundations of biology.

Contents

Modern cell theory

History of cell theory

External links

References

Modern cell theory

The generally accepted parts of cell theory include:
# The cell is the fundamental unit of structure and function in living things.
# All cells come from pre-existing cells by division.
# Energy flow (metabolism and biochemistry) occurs within cells.
# Cells contain hereditary information which is passed from cell to cell during cell division
# All cells are basically the same in chemical composition.
# All known living things are made up of cells.
# Some organisms are unicellular, made up of only one cell.
# Others are multicellular, composed of countless number of cells.
This theory also contains two exceptions:
# Viruses are considered by some to be alive, yet they are not made up of cells.
# The first cell did not originate from a preexisting cell.
Nuclear pore

History of cell theory

The cell was first discovered and named by Robert Hooke in 1663. He remarked that it looked strangely similar to ''cellula'' or small rooms which monks inhabited, thus deriving the name. However what Hooke actually saw was the dead cell walls of plant cells also known as cork. These cell walls lacked the nucleus and other organelles found in most living cells. The first man to witness a live cell under a microscope was Anton van Leeuwenhoek, who in 1674 described the algae ''Spirogyra''. Van Leeuwenhoek also described bacteria which he referred to as animacules.
as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of to Cell theory" ^[1]. The idea that cells were separable into individual units was proposed by Ludolph Christian Treviranus^[2] and Johann Jacob Paul Moldenhawer^[3]. All of this finally led to Henri Dutrochet formulating one of the fundamental tenets of modern cell theory by declaring that {{cquote|The cell is the fundamental element of organization^[4]
Credit for developing Cell Theory is usually given to two scientists, Theodor Schwann, a zoologist and Matthias Jakob Schleiden, a botanist. In 1839 these two scientists suggested that cells were the basic unit of life. Their theory accepted the first two tenets of modern cell theory. However the cell theory of Schleiden differered from modern cell theory in that it proposed a method of spontaneous crystallization that he called "Free Cell Formation"^[5]. In 1858, Rudolf Virchow concluded that all cells come from pre-existing cells thus completing the modern theory.

External links

★ http://fig.cox.miami.edu/~cmallery/150/unity/cell.text.htm

★ http://www.biology.arizona.edu/cell_bio/tutorials/cells/cells3.html

★ http://www.edu.pe.ca/vrcs/2003/courses/9science/timeline.htm

★ http://www2.bc.edu/~strother/GE_146/lectures/12.html

★ http://www.cellsalive.com

References

1. The American Naturalist, Vol.73 pgs 517-537
2. Treviranus, Ludolph Christian 1811, "Beyträge zur Pflanzenphysiologie"
3. Moldenhawer, Johann Jacob Paul 1812, "Beyträge zur Anatomie der Pflanzen"
4. Dutrochet, Henri 1824, "Anatomical and Physiological Researches on the Intimate Structures of Animals and Plants, and Their Motility"
5. Schleiden, Matthias Jakob 1839,"Contributions to Phytogenesis"