Cell theory
In biology, cell theory is a scientific theory that describes the properties of cells, which are the basic unit of structure in all organisms and also the basic unit of reproduction. The initial development of the theory, during the mid-17th century, was made possible by advances in microscopy; the study of cells is called cell biology. Cell theory is one of the foundations of biology.The observations of Hooke, Leeuwenhoek, Schleiden, Schwann, Virchow, and others led to the development of the cell theory. The cell theory is a widely accepted explanation of the relationship between cells and living things.
The three tenets to the cell theory are as described below:
All living organisms are composed of one or more cells.
The cell is the most basic unit of life.
All cells arise from pre-existing, living cells.
The first two tenets were postulated in 1839, and the third was proposed by Rudolf Virchow around 1855.[1]
HistoryEdit
Drawing of the structure of cork by Robert Hooke that appeared in Micrographia.
The cell was first discovered by Robert Hooke in 1665. He examined (under a coarse, compound microscope) very thin slices of bottle cork and saw a multitude of tiny pores that he remarked looked like the walled compartments a monk would live in. Because of this association, Hooke called them cells, the name they still bear. However, Hooke did not know their real structure or function.[2] What Hooke had thought were cells were actually just empty cell walls of plant tissues, but without ever thinking that cells could be alive, and also since his microscope had a very low magnification, making it difficult to observe the internal organization of the structure he had discovered, he did not think his "cellulae" could be alive.[3] Hooke's description of these cells (which were actually non-living cell walls) was published in Micrographia.[4] His cell observations gave no indication of the nucleus and other organelles found in most living cells.
Robert
The three tenets to the cell theory are as described below:
All living organisms are composed of one or more cells.
The cell is the most basic unit of life.
All cells arise from pre-existing, living cells.
The first two tenets were postulated in 1839, and the third was proposed by Rudolf Virchow around 1855.[1]
HistoryEdit
Drawing of the structure of cork by Robert Hooke that appeared in Micrographia.
The cell was first discovered by Robert Hooke in 1665. He examined (under a coarse, compound microscope) very thin slices of bottle cork and saw a multitude of tiny pores that he remarked looked like the walled compartments a monk would live in. Because of this association, Hooke called them cells, the name they still bear. However, Hooke did not know their real structure or function.[2] What Hooke had thought were cells were actually just empty cell walls of plant tissues, but without ever thinking that cells could be alive, and also since his microscope had a very low magnification, making it difficult to observe the internal organization of the structure he had discovered, he did not think his "cellulae" could be alive.[3] Hooke's description of these cells (which were actually non-living cell walls) was published in Micrographia.[4] His cell observations gave no indication of the nucleus and other organelles found in most living cells.
Robert