Classification To avoid confusion caused by regional names, biologists use a classification system to group organisms in a logical manner and to assign names. Linnaeus developed the method used to name organisms and group them in a logical manner which gives a universally accepted name. the scientific name is the universally accepted name given to every species.

binomial nomenclature – the system of naming organisms according to genus and species Taxonomy is used to classify and assign each organism a universally accepted name. In taxonomy, each level is called a taxon: Kingdom Phylum Class Order Family Genus Species

Linnaeu’s hierarchial system of classification Grizzly bear Black bear Panda bear Red fox Coral snake Abert squirrel Sea Star Animalia Kingdom Chordata Phylum Mammalia C;lass Carnivora Order Ursidae Family Ursae Genus Ursus arctos Species

Modern Evolutionary Classification Which Similarities Are Most Important? Early systems of classification grouped organisms together based on visible similarities appendages Conical shell

Evolutionary Classification Organisms are grouped into categories that represent lines of evolutionary descent, or phylogeny, not just physical similarities Phylogeny – evolutionary relationships among organisms

Classification Using Cladograms A cladogram is a diagram that shows evolutionary relationships among organisms based on shared derived characters.

Similarities in DNA and RNA African vulture Marabou stork American vulture The American vulture and the Marabou stork are more closely related than the American vulture and the African vulture Similarities at the DNA level in the genes of organisms can be used to help determine classification

Molecular Clocks By comparing the DNA sequences of two or more species, biologists estimate how long the species have been separated

three-domain system The three-domain system was first invented in 1990, but not generally accepted until later. One main characteristic of the three-domain method is the separation of Archaea and Bacteria previously grouped into the single kingdom Bacteria (also called Monera). Streptococcus bacteria can live in a persons body and cause illnesses like strep throat Archaea are the most ancient organisms on Earth and they exist in extreme environments

three-domain system The majority of biologists accept the domain system, but a large minority use the five-kingdom method.

Extremophiles Extremophilic microbes can be found thriving in some of the most hostile environments imaginable — swimming in near-boiling water eating rocks in subzero temperatures where radiation levels rival nuclear reactors

What is an Extremophile? An extremophile is an organism that thrives under "extreme" conditions. The term frequently refers to prokaryotes and is sometimes used interchangeably with Archaea. extremophiles come in all shapes and sizes our understanding of the diversity of extreme habitats increases daily.

Terms Used to Describe Extremophiles They are a combination of the suffix –phile, meaning "lover of," and a prefix specific to their environment. For example, acidophiles are organisms that love (phile) acid (acido). Acidophile: An organism that grows best at acidic (low) pH values. Alkaliphile: An organism that grows best at high pH values. Anaerobe: An organism that can grow in the absence of oxygen.

Review In biology, binomial nomenclature is the formal system of naming specific species. Each species name is in (modern scientific) Latin and has two parts, so that it is popularly known as the “scientific name " of the species. The species is the lowest level in the system for classifying organisms.

Genus and species As the words "binomial", "binominal" and "binary" the scientific name of each species is formed by the combination of two words the genus name (also called the generic name). a second word identifying the species within that genus, (also called the specific epithat)

Genus and species Species names are usually in italics; for example, Homo sapiens. When handwritten, they should be underlined; for example, Homo sapiens. Each name should be underlined individually. The genus name is always written with an initial capital letter. For example, the entire tiger species is Panthera tigris

Cladistics Cladistics is the hierarchical classification of species based on evolutionary ancestry. Cladistics is distinguished from other taxonomic systems because it focuses on evolution rather than similarities between species Cladistics generates diagrams called cladograms that represent the evolutionary tree of life. DNA and RNA sequencing data are used in cladistics. The word cladistics is derived from the ancient Greek meaning "branch."

Kingdom Protista