Classification Notes

Taxonomy Naming and grouping organisms according to their characteristics and evolutionary history.

Aristotle Greek philosopher who first attempted to classify living organisms Over 2000 years ago

Aristotle He classified living things into two groups: Plants Animals

Aristotle Why did his system create problems? Not all living things are plants and animals Even plants and animals are very diverse Our knowledge of life has changed

Carolus Linnaeus Swedish scientist who developed our modern system of classification. 1707 - 1778

Carolus Linnaeus Used morphology (form and structure) to categorize organisms

Carolus Linnaeus Developed a hierarchy of levels in his system Kingdom King Phylum Phillip Class Came Order Over Family For Genus Good Species Soup

Species Remember that a species is a group of organisms that can mate and reproduce fertile offspring Not a clear cut definition

Common Names Most people use common names for organisms This causes problems 13 lined ground squirrels are often called gophers

Scientific Names Scientific names solve the naming problem Latin is used for most scientific names.

Binomial Nomenclature All organisms are given a genus and a species name. This way all people can use the same name to identify organisms

Genus and Species The genus name comes first and begins with a capital letter. Ex. Felis (it can be abbreviated as F. The species names comes second and begins with a lower case letter. Ex. domesticus *Both the genus and species names are usually italicized and often underlined. Ex. Felis domesticus

How do we classify organisms today? Not so much on physical similarities (can be based too much on opinions). Scientific evidence is a better way to do this.

Evidence for Classification Chromosome Structure Biochemical Similarities Embryology DNA Sequencing Reproduction

Systems of Classification Linnaeus used 2 Kingdoms Plant Animal

The Three-Domain System Molecular analyses have given rise to a new taxonomic category that is now recognized by many scientists. The domain is a more inclusive category than any other — larger than a kingdom. Copyright Pearson Prentice Hall

The Three-Domain System The three domains are: Eukarya, which is composed of protists, fungi, plants, and animals. Bacteria, which corresponds to the kingdom Eubacteria. Archaea, which corresponds to the kingdom Archaebacteria. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Domain Bacteria Domain Bacteria Members of the domain Bacteria are unicellular prokaryotes. Their cells have thick, rigid cell walls that surround a cell membrane. Their cell walls contain peptidoglycan. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Domain Archaea Domain Archaea Members of the domain Archaea are unicellular prokaryotes. Many live in extreme environments. Their cell walls lack peptidoglycan, and their cell membranes contain unusual lipids not found in any other organism. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Domain Eukarya Domain Eukarya The domain Eukarya consists of organisms that have a nucleus. This domain is organized into four kingdoms: Protista Fungi Plantae Animalia Copyright Pearson Prentice Hall

Modern Kingdoms Animalia Plantae Fungi Protista Archaebacteria Eubacteria

Animalia Multicellular heterotrophs

Plantae Multicellular autotrophs

Fungi Most are multicellular Yeast is unicellular Absorb food through cell walls

Archaebacteria Unicellular prokaryotes Related to first life forms Live in harsh environments

Eubacteria Unicellular prokaryotes Includes most bacteria

Classification of a human Kingdom = Animalia Phylum = Chordata Class = Mammalia Order = Primate Family = Hominid Genus = Homo Species = sapien