EMERGENCE OF CELL THEORY:
It is a fundamental theory about cell.In 1838 Schleiden, a German botanist, concluded that, despite differences in the structure of various tissues, plants were made of cells.In 1839, a German zoologist, T.Schwan, published a comprehensive report on the cellular basis of animals. Both of them proposed the cell theory.The important feature s of cell theory are:
- The body of all the living organisms are composed of one or more cells.
- Cell is the structural and functional unit of life. It is a 'de novo' structure i.e could arise from non-cellular materials.
A German pathologist Rudolf Virchow made a convincing case and added a third point to the cell theory which was the correction of the the statement that a cell is a 'de novo' structure.He proposed that cell can only be be arises by the division of a pre-existing cell, it is not a de novo structure.
Cell theory brought a great revolution in the field of biology which established that the function of an organism is the result of activities and interaction of the cell units.
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WHAT IS A CELL?
CELL is the most puzzling
mystery of nature about....
INTRODUCTION OF CELL:
CELL is the most puzzling mystery of nature about which it is believed that the day scientists will understand it fully, they would be able to unravel the secret of life and death. The discovery of cells and their structure became possible with the development of optical lenses and with the construction of compound microscope,which was invented by David Jansen in 1590 and in 1610 Galileo an Italian astronomer and physicist designed it properly.
CELL THE BASIC UNIT UNIT OF LIFE:
HISTORY/DISCOVERY:
The term cell (Greek, Kytos-cell; La; Cella-Hollow space) was first used by Robert Hooke (1665) to describe his investigations on the structure of cork He observed empty spaces when he put the thin slice of wooden cork under the compound microscope.He called these room or empty spaces as "Cella" which means hollow.These spaces that he observed were the dead cells of plants with only cell wall looks like a honey comb structure.Robert hooke discussed his observartion in his book MICROGRAPHIA.In this book, he gave 60 ‘observations’ in detail of various objects under a coarse, compound microscope
Later Robert Brown(1831) discovered a spherical body, the nucleus in the cells of orchids. The fact that living organisms have a cellular organization was emphasized by Schleiden(1838) and Schwann (1839). Schwann, observed that the nucleus was surrounded by a fluid in the cell. His observation thus, changed the definition of cell and he described the "Cell as a structure which consists of a nucleus surrounded by a semi fluid substances enclosed by a membrane"later, it was pointed out, that the structure of a cell in animals and plants is similar with only one difference, that plant cell has a cell-wall in addition to the cell membrane.
DEFINITION:
Cell is the basic structural and functional unit of life.It is the smallest part of living organisms.Cell can also be defined as "a small piece of cytoplasm contain a nucleus and covered by an outer protective layer called cell membrane".
EMERGENCE OF CELL THEORY
It is a fundamental theory about
the cell which was proposed by....
