Classification

- Traditionally, organisms are classified according to a system first proposed by Carl Linnaeus

- Groups living things according to their charcteristics and the structures that make them up

- In the Linnaean system, living things are fist divided into kingdoms, which are then subdivided into smaller groups:

- Phylum

- Class

- Order

- Family

- Genus

- Species

- Scientists put forward new models of classification as knowledge of the biochemical processes taking place inside organisms developed and microscopes improved

- Carl Woese proposed the three-domain system - using evidence gathered from new chemical analysis techniques (RNA sequence analysis), he found that in some cases, species thought to be closely related in traditional classification systems are in fact not as closely related as first thought

- ARCHEA - primitive bacteria, which can be found in extreme places, such as hot springs and salt lakes

- BACTERIA - contains true bacteria (E. coli) - they may often look similar to archea but there are lots of biochemical differences between them

- EUKARYOTA - includes a broad range of organisms, such as fungi, plants, animals and protists

- In the binomial system, every organism is given its own two-part Latin name

- The first part refers to the genus that the organism belongs to - this gives you information on the organisms ancestery

- The second part refers to the species - humans are known as 'Homo sapiens' because our genus is 'Homo' and our species is 'sapiens'

- Binomial system is used worldwide and means that scientists, in different countries or who speak different languages, all refer to a particular species by the same name, which avoids potential confusion

- The trees show how scientists think different species are related to each other

- They show common ancestors and relationships between species

- The more recent the common ancestor, the more closely related the two species, and the more characteristics they are likely to share

- Scientists analyse lots of data to work out evolutionary relationships - for living organisms, they use current classification data (DNA analysis and structural similarities) - for extinct species, they use the fossil record