Taxonomy and Classification Biology I – The History of Classification 17.3 Domains and Kingdoms

Early Systems of Classification  Classification: the grouping of objects or organisms based on a set of requirements  Aristotle classified organisms over 2,000 years ago His system was based on the presence or absence of blood His system had two mains groups plants and animals

Linnaeus’s System  In the 1700’s an important change in classification occurred  Carl Linnaeus made classification a formal science called taxonomy  Taxonomy is a science that identifies, names, and classifies organisms based on their biological relationships  Linnaeus’s system used binomial nomenclature

Naming Organisms  Binomial nomenclature: is the science of naming living things with two names  All living things need a name that applies to them and the name needs to mean the same thing to all people so it has to be in one language (Latin)  We give things two names called Genus and Species  Homo sapiens  The first name is always capitalized and both names are underlined or italicized

Comprehension Check What was the major difference between Aristotle’s system and Linnaeus’ system of classification? Why is binomial nomenclature important to scientists?

Modern Classification

Taxonomic Categories: Kingdoms  Taxonomic Systems always divided living things into 5 Kingdoms Monera (Bacteria) Protista Animals Plants Fungi  Modern researches found that there were actually too many differences between types of bacteria and they divided the Monera kingdom into two making a 6 Kingdom system Eubacteria Archaebacteria

Taxonomic Categories: Domains  Even more recently, researches have found that organisms can be placed into larger groups based on their rRNA  This research is new because scientists have only recently (for the past 50 years or so) been able to study and understand RNA.  Domains are based on rRNA: Bacteria (includes the Eubacteria) Archaea (includes the Archaebacteria) Eykarya (includes the Protists, Fungi, Plants, Animals)

Bacteria Domain  Unicellular  Prokaryotic Cells  Cell walls made of peptidoglycan  Very diverse group including free living organisms and deadly parasites  Some can photosynthesize, some can not

Bacteria  How small are they?  What can they do?  Where are they found?  What can get rid of them?

Archaea Domain  Unicellular  Prokaryotic  Live in extreme environments  Most will be killed by oxygen  Some can photosynthesize or chemosynthesize, some can not

Eukarya Domain  Some unicellular, but most are multicellular  All have cells with a nucleus  4 Sub-groups (Kingdoms) Protista: things that can not be classified as plant, animal or fungi Fungi: Secrete digestive enzymes into their food Plant: Photosynthesizers Animals: Heterotrophs, high amount of diversity

Plants  Close your eyes and think about sitting in the middle of a green field in summer. Think about all of the green plants that you would see around you.  How can we keep track of all of these different types of plants?

Things you might need to know to understand plant keys Opposite or Alternate Compound or Simple Leaflet Petiole Leaf Scar Sinuses, Lobes and Veins Single/Double Toothed

Comprehension Check What is the major difference between Archaebacteria and Eubacteria? What would you be more likely to find in this classroom Archaebacteria or Eubacteria?

Human Systems  Multicellular organisms have specialized cells and systems  10 Body System (Integumentary System Not Shown Here!)