Classification

Classification

• Traditionally, organisms have been classified according to a system first proposed in the 1700s by Carl Linnaeus, which groups living things according to their characteristics and the structures that make them up.
• In this system, known as the Linnaean system, living things are first divided into kingdoms.
• The kingdoms are then subdivided into smaller and smaller groups: phylum, class, order, family, genus, species.
• As knowledge of the biochemical processes taking place inside organisms developed and microscopes improved (which allowed us to learn more about the internal structures of an organism), scientists put forward new models of classification.
• In 1990, Carl Woese proposed the three-domain system. Using evidence gathered from new chemical analysis techniques such as RNA sequence analysis, he found that in some cases, species thought to be closely related in traditional classification are in fact not as closely related as first thought.
• The three domains were:

Archaea- Organisms in this domain were…