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The cell

THE CELL

Organisms differ from each other structurally and functionally but all are made up of cells.
All living organisms carry out certain basic functions.
The basic structural and functional unit of an organ is the cell.

Discovery of the cell:

Robert Hooke in 1665 observed slices of cork under a simple magnifying device. Cork is a substance which comes from the bark of a tree. He noticed partitioned boxes or compartments in the cork slice. These boxes appeared like a honeycomb. Each box was separated from the other by a wall.

Dead cork cells as observed by Sir Robert Hooke

Hooke coined the term ‘cell’ for each box. The word cell is derived from the Latin word “cellulae” which means “a little room”.
Nowadays, compound microscope is used to magnify the image.

History of cell:

Sr. No.	Scientist	Year	Contribution
1.	Robert Hooke	1665	Discovered and coined the name cell.
2.	Leeuwenhoek	1674 1678	Free bacterial cells in pond water. Discovered sperms in different organisms like humans, dogs, rabbits, frogs, fish, insects etc.
3.	Robert Brown	1831	Discovered nucleus in plant cells.
4.	J.E.Purkinje	1839	Discovered protoplasm and defined it as a living matter of the cell.
5.	Haeckel	1866	Discovered that nucleus is responsible for storage and transmission of hereditary material from one generation to the other.
6.	Jakob M. Schleiden	1838	All plants are made up of cells.
7.	Theodor Schwann	1839	All plants and animals are made up of cells thus cell is a basic structural unit of life thus proposed cell theory.
8.	R.Virchow	1855	Modified cell theory.

Modern Cell Theory as modified by R. Virchow (1855)

All organisms are made up of cell and cell products.
Cells are the basic structural and functional unit of life because all metabolic reactions take place inside the cell only.
All cells arise from the pre-existing cells.
Each organism begins its life as a single cell only.