Cell
Theory
Cell is the basic structural and
functional unit of all living
organisms.
The cell theory
Was first formulated in 1838 and 1839 by a
BOTANIST called MATTHIAS SCHLEIDEN and the
ZOOLOGIST called THEODOR SCHWAN .
In their theory they also discuss how organisms can
be grouped according to the number of cells in
their bodies.
 UNICELLULAR – one cell organism.
 MULTICELLUAR – more than one cell in a body of an
organism.
The cell theory
• There are many Scientists who produced
studied discoveries of cells just before
and after the cell theory ,Right below are
the names of the scientists and the major
discoveries that influenced the Cell
Theory.
1. ROBERT HOOK – in 1665 he discovered
a cell ; he saw the remains of dead
cells in a piece of cork.
The cell theory
ANTONIE VAN
LEEUWENHOEK
 Was the first person to study animal cells under a
Microscope in 1674
 He made specialized lenses which he used to
discover and to study bacteria , protist , blood
cells and sperm cells.
The cell theory
ROBERT BROWN
 In 1831, while investigating the
fertilization mechanisms of plants, he
noted the existence of a structure
within the cells of orchids, as well as
many other plants, that he termed the
“nucleus” of the cell.
THE CELL THEORY
PURKINJE
A physiologist who is regarded as the
correct use of the term ( ‘living
matter’ )
The cell theory
SCHIMPER AND MEYER
In 1880 the two described plastids in plants , they
said that plastids are double membrane
organelles that are found in the cells of plants and
algae e.g. , chloroplast.
The cell theory
HAECKEL
1886, He was the first person to establish
the importance of the chromatin network
as a carrier of the hereditary
characteristics.
The cell theory
ROBERT VIRCHOW
Said that all cells develop from
already existing cells .
Cell theory
LWOFF
In 1962 the cell theory of LWOFF stated that when
organisms are studied on a cellular level , the concept
of unity clearly visible, that is
1. Unity of structure – all cells consists of the
nucleus in cytoplasm .
2. Unity of function – all cells haver the same basic
metabolism.
3. Unity of composition- same macromolecules are
found in all cells.