How Can Microbes Be Classified

Bacteria

Unicellular, lack nuclei, contain peptidoglycan cell walls, and reproduce asexually

Archaea

Unicellular, lack nuclei, lack peptidoglycan (polymers instead), and often found in extreme environments

Fungi

Eukaryotic organisms that obtain food from others and possess cell walls

Molds

Multicellular fungi that grow as long filaments and reproduce via sexual/asexual spores

Yeasts

Unicellular fungi that reproduce asexually by budding

Protozoa

Single-celled eukaryotes similar to animals in nutrient needs; most are capable of locomotion.

Pseudopods

Cell extensions in protozoa that flow in the direction of travel for movement

Cilia

Numerous short protrusions on protozoa used to propel the organism through its environment

Flagella

Long, whiplike cell extensions used for locomotion; fewer in number than cilia

Algae

Unicellular or multicellular photosynthetic eukaryotes categorized by pigmentation and cell wall composition

Viruses

Acellular particles consisting of a DNA or RNA core with a protein coat; replicate only inside living host cells

Helminths

Multicellular animal parasites, specifically parasitic flatworms and roundworms

Eukaryote

An organism with a membrane

Prokaryote

An organism lacking a nucleus; includes bacteria and archaea