The broadest and most general category of classification is the DOMAIN

The three domains are BACTERIA, ARCHEA, and EUKARYA  Organisms are classified into domains based on their cell type and structure

 Prokaryotes with cell walls containing peptidoglycan.  Survive in many environments  Can be aerobic or anaerobic  Can be autotrophs (make their own food) or heterotrophs  More abundant than any other organism  Only kingdom is BACTERIA

 Thought to be the oldest organisms  Diverse in shape and nutrition requirements  Some autotrophic, most are heterotrophic  They are extremophiles, meaning that they live in extreme environments  Only kingdom is ARCHAEA

 Organisms with a membrane- bound nucleus  Consist of the kingdoms: PROTISTA, FUNGI, PLANTAE, and ANIMALIA

 Eukaryotic organisms that can be unicellular, colonial, or multicellular  Classified into three groups: Algae (plant- like), Protozoans (animal- like), and fungus-like protozoans  They can be autotrophic or heterotrophic.  Example: Paramecium

 A fungus can be unicellular or multicellular  They absorb nutrients from organic materials in the environment  Heterotrophs  Lack motility (ability to move)  Have cell walls  Example: Mushroom

 Multicellular  Contain cell walls  Contain chloroplasts  Mostly autotrophic with a few heterotrophs  Possess cells organized into tissue  Example: Moss

 Heterotrophic  Multicellular eukaryotes  No cell walls  Cells are organized into tissues  Mostly motile  Example: Worm

Viruses are motile and contain genetic material, but are not placed in a classification category. This is because viruses do not contain cells, so they are not considered living. They are made of nucleic acid surrounded by protein.