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Cell IntroductionThe cell is regarded as a fundamental structural and functional unit of
life because the basic structure of all the living organisms is made up
of cells. Hence cell is known as the structural unit of life. Let us learn
about cell study and cell theory.
Landmarks in Cell Study
● Discovery of Cell: Cell was discovered by an English scientist
Robert Hook in the year 1665. He published this information in
his book ‘Micrographia’. He observed that dead cells in a thin
cork slice in a self-made microscope. And this was the
beginning of cell study and discovery.
● Why were they named cells? Because the cells looked like the
small rooms of a Buddhist monastery which were called
cellullae. Hence the name cell was given.
● Anton Von Leeuwenhoek designed an improved microscope
and observed first free-living cells (Bacteria) in the year.
● Robert Brown A Scottish Botanist discovered nucleus in the
year 1831.
, ● A French Zoologist Dujardin discovered the semifluid living
material inside a cell and named it Sarcode.
● Purkinje in the year 1840 renamed it as ‘Protoplasm – The First
Substance’.
● A cell can be viewed as an enclosed vessel, within which
innumerable chemical reactions take place simultaneously.
These reactions are under very precise control so that they
contribute to the life and formation of new cells.
Cell Theory
A German botanist M.J. Schleiden in the year 1838 found out that all
plants are made of cells. A German Zoologist T. Schwann in the year
1839 also said that all the animals are made up of cells. They
commonly presented their findings as Cell Theory.
Postulates of Cell Theory are
● All living organisms are composed of cells.
● All cells are basically alike in structure and functions.
, ● The function of an organism as a whole is the result of the
activities and interactions of constituents of the cell.
Modern Cell Theory
In the year 1858 scientist Rudolf Virchow presented the idea ‘Omnis
Cellula e Cellula’, which means that all living cells arise from
pre-existing cells. After addition of this postulate in the cell theory, it
was called Modern Cell Theory.
Cell Facts
● Cells vary in shape and size.
● The nerve cell is the longest cell in our body. It can be about
1m long.
● Ostrich egg is the largest cell.
● Red Blood Corpuscles are the smallest cell in the human body
and female ovum is the largest cell in the human.
● Some organisms may be made up of a single cell (Unicellular
Organisms), eg; Amoeba. Others are multicellular.
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