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CELLS
Cell Theory, Endosymbiosis &
Comparing Cells
Cell Theory
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The cell theory consists of three basic
principles:
Cells are the basic units of all life.
All organisms are made up of one or
more cells.
All cells arise from existing cells.
Comparing Prokaryotic and
Eukaryotic Cells
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Prokaryotic Cells
Simple cells that
consist of little more
than a cell
membrane, some
DNA, and cytoplasm
Do not have a
nucleus or any
organelles
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Eukaryotic Cells
Complicated cells
Contain a nucleus and
organelles
Endosymbiotic Theory
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Symbiosis occurs when two different species
benefit from living and working together.
When one organism actually lives inside the
other it's called endosymbiosis.
Organism 1
Organism 2
Endosymbiotic Theory
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The endosymbiotic theory describes how a
large host cell and ingested bacteria could easily
become dependent on one another for survival,
resulting in a permanent relationship.
Over millions of years of evolution, mitochondria
and chloroplasts have become more specialized
and today they cannot live outside the cell.
Comparing Plant and Animal Cells
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Plant and animal cells share many characteristics
Both types of cells are eukaryotic and have
many of the same organelles
They both have cell membranes
There are, however, 3 structures found in plant
cells that are not in animal cells
Plant Cell Structures Not Found in
Animal Cells
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Cell Wall: tough, rigid outer covering that protects plant
cells and helps them maintain their shape; contains
cellulose
Chloroplasts: these structures enable plant cells to make
sugars using photosynthesis
Large, Central Vacuole: although animal cells may
contain vacuoles, they are usually small; plant cells have
one large, central vacuole used to absorb water or ions or
store wastes
Animal Cell Structures Not Found
in Plant Cells
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Animal cells have a centriole and plants do not
Animal cells also have a cytoskeleton in the
cytoplasm for support