Single Celled Organisms
Unicellular Organisms
• Some organisms are made up of only one cell.
• We call these organisms unicellular which
means one-celled.
• These organisms are much simpler than most
organisms that are made up of many cells.
Archea/Eubacteria
• The Archea/Eubacteria Kingdom consists of
unicellular life forms.
• Prokaryotic cells are far simpler and more
basic than the cells of other life forms.
No Nucleus
• Archea/Eubacteria cells have no nucleus so
they are prokaryotes.
• They are also missing many of the organelles,
or parts, commonly found in other cells.
• For this reason, Archea/Eubacteria are
thought to be very distantly related to other
life forms.
• Bacteria is one type of Archea/Eubacteria
Bacteria
Protists
• The Protista Kingdom consists of
unicellular life forms (life forms with only
one cell).
• All protists are
eukaryotes –
they have a nuclues.
Protist vs Bacteria
• The primary difference between protists and
Eubacteria/Archea (bacteria) is that protists
are more complex, having a nucleus.
This bacteria is a single
celled organism, but it
has no nucleus. It is in
the Kingdom
Eubacteria.
Many protists appear to be
both plant and animal. Like
plants, they are green, and
can create their own food.
However, like animals, they
have moving body parts, and
are able to move around
their environments.
• How do you think this protist – named
Euglena – moves around?
• See the whip like tail
on this drawing of
the Euglena?
• The tail helps the
single celled
organism move
around.
• The Euglena can
make its own food so
it is both plant and
animal like.
Biologists believe that the
ancient protists were the
ancestors of plants and
animals.