Classification of Organisms

So scientists around the world know specifically what another scientist is talking about.

The science of classifying organisms according to the inferred relationships - artificial means by which we can deal with huge biodiversity and organize organisms so that relationships can be made

1) identify organisms 2) provide a basis for recognizing natural grouping of living things - the current system of classification is the binomial system of nomenclature developed by Carl Linnaeus

• A method of naming organisms by using two names - the genus name and the species name • based on an organism’s physical and structural features (assumption that the more features that organisms have in common, the closer their relationship) • Genus: always cap • Species: always lowercase • both are italicized or underlined to make them stand out in written text

Latin is considered a ‘dead’ language (this does not mean it is not spoken it means that it doesn’t evolve. Because it doesn’t evolve Latin is the universal language of science and anyone in any part of the world will be able to understand the binomial Latin name of an organism.

• Genus then species • genus may appear alone (as it can contain many different species) however, the species can never be alone (as it is the lowest level of classification)

• the genus and species are pat of 7 main taxa • taxa: categories used to define organisms • each level becomes more specific as one goes from top to bottom • the increase in similarities are in anatomy, embryology, and ancestry • as you go down the pyramid you increase in similarity but decrease in number Kingdom Phylum Class Order Family Genus Species

• originally was only a two class system made of plantae and animalia • discovery of single-celled organisms that have plant and animal traits led to third kingdom called Protista or Protocista • Because bacteria and cyanobacteria lacked a true nucleus (ie prokaryotes meaning before nucleus) a fourth kingdom was made called monera was formed • it acknowledged that mushrooms were different enough from plants to be placed in its own kingdom called Fungi

Carl Woese and other researchers had discovered that a group called archaebacteria (‘ancient’) was significantly different from bacteria (now called eubacteria meaning ‘true’ bacteria) - this replaced the Kingdom monera into archaebacteria and eubacteria

• classification of organisms have been split into three domains 1) Eukarya: eukaryotes, eu meaning true and karyotes meaning nucleus, contains the kingdoms anamalia, plantae, fungi, and protista 2) archea: archaebacteria 3) bacteria: eubacteria

General Characteristics - simple organisms lacking a nucleus meaning they are prokaryotic - either heterotrophs or autotrophs - all can reproduce asexually - they live nearly everywhere Cell Wall - often have a cell wall - made of peptidoglycan which is made of protein and subunits Representative Organism - bacteria - cynobacteria

General Characteristics - prokaryotic - heterotrophs - live in salt lakes, animal guts, and hot springs Cell Wall - has a cell wall - does not contain peptidoglycan Representative Organisms - methanogens - extreme thermophiles - extreme halophiles

General Characteristics - most are unicellular some multicellular - some are autotrophs some are heterotrophs some are both - reproduce sexually and asexually - live in aquatic and moist habitats Cell Wall - no cell well Representative Organisms - algae - protozoans

General Characteristics - most are multicellular - all are heterotrophs - reproduce sexually and asexually - most are terrestrial Cell Wall - present and made of chitin Representative Organisms - mushrooms - yeasts - bread molds

General Characteristics - all are multicellular - all are autotrophs - reproduce sexually and asexually - most are terrestrial Cell Wall - present and made of cellulose Representative Organisms - mosses - ferns - conifers - flowering plants

General Characteristics - all are multicellular - all are heterotrophs - most reproduce sexually - live in terrestrial and aquatic habitats Cell Wall - absent Representative Organisms - sponges - worms - lobsterss - starfish - fish - reptiles - birds - mammals

• the history of a group of species or a group of organisms • this relationship can be represented in a phylogenetic tree where the tree starts from the most ancestral form and branches out to all other descendants • normally the branch lengths are proportional to the predicted evolutionary time between organisms and sequences

• a two part key that is used to identify living things • Greek meaning ‘divided into two things’ • consists of 2 part statement describing a single characteristic of an organism • at each step the user is directed to another part depending upon the choice • these characteristics should not be vague or subjective and should have only one possible answer there are two types 1) branch method 2) list method