ARCHAEA: Archaeons are single celled microorganisms that lack nuclear membranes and consist of prokaryotic cells. These organisms have very distinguishable biochemistry and unique RNA. Those apart of the Archaea domain are considered to be some of the oldest species of organisms known on Earth.
BACTERIA: Bacteria are also single celled microorganisms that do not have nuclear membranes. Bacteria are also made up of prokaryotic cells. Bacteria have several different shapes and sizes, and were also some of the oldest organisms to be discovered on earth. Bacteria, although not always visible, can be found virtually anywhere on Earth.
EUKARYOTES: Eukaryotes organisms have a membrane bound nucleus and are made up of eukaryotic organisms rather than prokaryotic organisms. Eutes have membrane-bound organelles. The nucleus consists of genetic material, which is surrounded by the nuclear envelope. Eucaryotes are the only organisms that have the ability to form multi-cellular organisms. Those apart of the Eukarya domain have the ability to reproduce sexually, asexually, or even both ways.