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Cell Organization Notes
 All living things are composed of one or more cells.
 Unicellular organisms are composed of one cell which needs to
carry out life processes on its own
 Multi-cellular organisms are composed of many cells and have
specialized structures to help them carry out life processes
Organization of Life
Cells  Tissues
 Organs  Organ System 
Organism
History of
the
Robert Brown
discovers the
nucleus of the cell
Cell
Theodor Schwann says that
the cell is the basic unit of
structure in plants

Robert Hooke
discovers dead
cork cells
Mathius Sleiden says
that the cell is the
basic unit of
structure in animals
Rudolph Virchow
says all living
things come from
other living cells
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Cell Theory
 All organisms are composed of one or more cells.
 The cell is the basic unit of life in all living things.
 All cells come from existing cells.
Exceptions to the Cell Theory
 Where did the first cell come from?
 Viruses- (can’t reproduce by themselves)
Similarities of Cells
1) All cells have a cell membrane
-Cell membrane- acts as a barrier between the inside of the
cell and the cell’s environment
2) All cells have hereditary material (DNA)
3) All cells have cytoplasm and organelles
-Organelles- structures that help cells live, grow, and
reproduce
-Cytoplasm- jelly like material that fills up the cell
4) Cells are small in size
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