Taxonomy
• Taxonomy- the practice and science of
classification
– Why do scientists classify organisms?
• Used to organize living things into groups so that they
are easier to study
• Helps identify the relationship between organisms
• Helps to avoid confusion in naming and identifying
organisms
• Taxon- divisions with subdivisions; from the
most specific taxon (species) to the most
general (kingdom)
• Naming species
– Species- group of organisms capable of interbreeding and
producing fertile offspring
– Each species is identified by a binomial Latin name, which
refers to both the genus and species, with genus
capitalized and species in lower case. The whole thing is
italicized or underlined
• Human = Homo sapiens
• Great White Shark = Carcharodon carcharias
• Megalodon Shark = Carcharadon megalodon
• Current classification system
– Three Domains- all life dividing into 3
Domains
1. Bacteria- single- celled microorganisms; they
are prokaryotes, which means they have no
nucleus or organelles in their cells
2. Archaea- single celled microorganisms; also
prokaryotes. When first discovered (1977),
considered bacteria. After further research,
they have no close relationship to bacteria
3. Eukarya- organism with eukaryotic cells
(nucleus and other membrane bound
organelles)
• 6 kingdoms
1. Eubacteria- prokaryotes, unicellular; found in
every habitat on earth
2. Archaebacteria- prokaryotes; unicellular; more
closely related to eukaryotes than bacteria;
many species found in ocean
3. Protista- simple eukaryotes; either uni or
multicellular without specialized tissues
4. Fungi- eukaryotes; unicellular and multicellular;
heterotrophic decomposers
5. Plantae- eukaryotes; multicellular; cell walls;
autotrophic photosynthesizers
6. Animalia- eukaryotes; multicellular; no cell
walls; heterotrophic consumers
• How scientists classify organisms
– Methods: organisms can be placed into certain
taxonomical groups based on their…
• Morphology and anatomical structure
• Biochemical structure (RNA, DNA, Protein sequences)
• How scientists classify organims
– Phylogeny-evolutionary history of organism
• Phylogenetics- study of evolutionary relatedness
among various groups of organisms, which is
discovered through molecular sequencing data and
morphological data
• Phylogenetic tree- diagram showing the evolutionary
relationships among various biological species or other
entities that are known to have a common ancestor