Living Organisms are classified according to the types of cells they have; each Kingdom of living
organisms has different and unique cellular structures.
that do not have metabolic activities outside their host
Bacteria, Blue-Green algae, and the Archaea
Microscopic organisms with cell walls, single circular chromosomes, frequently
with flagella or cilia
Secrete cell walls outside their cell membranes
Some are photosynthetic or chemosynthetic autotrophs; others have heterotophic
metabolisms, living as saprophytes or parasites.
Very tiny cells, often forming spores, with rigid cell walls that never contain PDG.
Have a single circular chromosome, reproduce by binary fission, lack organelles, and live
in extreme environments. May be either chemosynthetic or photosynthetic autotrophs.
photosynthetic organisms found primarily in aquatic or marine environments,
Have cell walls of chitin or other carbohydrates, important source of atmospheric
Oxygen. Primary nitrogen fixers in marine and aquatic environments. High numbers are
used to indicate high nitrogen run-off in fresh water streams.
Includes the true Bacteria
Very small unicellular or colonial organisms (0.2-2.0 nanometers). Have cell walls
containing peptidoglycan, (PDG), have a
single circular chromosome, lack
membrane bound organelles, reproduce by binary fission. May have flagella, cilia, pili,
Bacterial Cell Morphology and Arrangement:
There are three common cell shapes
spherical cells that may be
as Diplococci, Tetrads, Streptococci, and
Staphylococci. Cocci are never
cylindrical cells of varying lengths that may be
Random (motile cells);
Streptobacillus, which are chains of bacilli;
are very tiny, oval bacilli
that are always motile, with random arrangement. May be either motile or nonmotile.
are spore formers.
helical, wormlike or spiral shaped cells that are always
motile; Spirochetes have axial
filaments that enable rapid swimming with a corkscrew motion. All
spirilli are motile