Taxonomy and ClassificationBiology I – 2011

17.1 The History of Classification17.3 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!)