Prokaryotic organisms fall into two domains: bacteria and archaea, which contain autotrophs and heterotrophs. Regardless of domain, prokaryotes share common traits of being single-celled organisms that are the smallest a... More »

Prokaryotic organisms belong to the kingdom Monera, which contains bacteria. The main classes of bacteria are eubacteria and archaebacteria. These prokaryotic organisms are unicellular and can live in different environme... More »

Prokaryotic cells are single cells that evolved before eukaryotes, which are organisms whose cells contain nuclei and organelles. A prokaryotic cell has no true nucleus or membrane-bound structures called organelles. Pro... More »

Autotrophs and heterotrophs differ in the way they obtain energy; autotrophs make their own energy whereas heterotrophs must consume other organisms to get their energy. Autotrophs are the producers of ecosystems, which ... More »

The two domains of prokaryotes, which are archae and bacteria, contain the common organisms of cyanobacteria, halophiles and hyperthermophiles. Prokaryotes occur in many forms, and some species are more common than other... More »

The five main groups of single-celled organisms are protozoa, archaea, bacteria, unicellular fungi and unicellular algae. While single-celled organisms can be either eukaryotic or prokaryotic, most are prokaryotes. The t... More »

Although members of the kingdom Animalia are almost exclusively multicellular, there are several unicellular organisms classified as animals, including species of bacteria, protozoa, fungi, algae and archaea. Bacteria ar... More »