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Classification Chapter 17

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•Almost 2 million species of organisms have been described

•Thousands more are discovered each year

•The total number of species ranges from 5 to 30 million

Species of Organisms

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What is Classification?Classification is the

arrangement of organisms into orderly groups based on their similarities

Classification is also known as taxonomy

Taxonomists are scientists that identify & name organisms

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Benefits of Classifying

•Accurately & uniformly names organisms •Prevents misnomers such as starfish & jellyfish that aren't really fish •Uses same language (Latin or some Greek) for all names

Sea”horse”??

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Confusion in Using Different Languages for Names

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Latin Names are Understood by all Taxonomists

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Early Taxonomists•2000 years ago, Aristotle was the first taxonomist•Aristotle divided organisms into plants & animals•He subdivided them by their habitat --Ex) land, sea, or air dwellers

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Carolus Linnaeus1707 – 1778

•18th century taxonomist

•Classified organisms by their form and structure

•Developed 7 levels of classification

•Developed naming system still used today

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Carolus Linnaeus•Called the “Father of Taxonomy”•Developed the modern system of naming known as binomial nomenclature- two-word name (Genus & species)

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Standardized Naming

Binomial nomenclature uses:•Genus species•Latin or Greek•Italicized in print•Capitalize genus, but NOT species•Underline when writing

Turdus migratorius

American Robin

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Binomial Nomenclature

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Classification Groups•Taxon ( taxa-plural) is a

category into which related organisms are placed

•There is a hierarchy of groups (taxa) from broadest to most specific

•Domain, Kingdom, Phylum, Class, Order, Family, Genus, species

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Hierarchy-Taxonomic Groups

DomainKingdom

Phylum Class Order Family

Genus Species

BROADEST TAXON

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KingPhillipCameOverForGoodSpaghetti

!

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Two Modern Systems

Six Kingdom System

Three Domain System

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The Six Kingdoms:

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• The prefix archae - comes from the Greek word "ANCIENT"

• Unicellular & Prokaryotic• Some are autotrophic and some are heterotrophic

• Live in extreme environments

Sewage treatment

plants, thermal

vents, etc.

KingdomArchaebacteria

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Kingdom Eubacteria

• Cause human diseases, are present in almost all habitats on earth

• Many bacteria are important environmentally and commercially. Live in the

intestines of animals

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Kingdom Protista“The odds and ends kingdom” Dumping ground of organisms that don’t fit into the other kingdomsEukaryoticUnicellular or Multicellular

Ex) Algae, Slime molds, Diatoms, and Protozoa

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Kingdom Fungi•Multicellular,

except yeast•Absorptive

heterotrophs (digest food outside their body & then absorb it)

•Decomposers Ex) yeast, mold,

mildew, & mushrooms

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Kingdom Plantae•Multicellular•Autotrophic•Absorb sunlight to make glucose – Photosynthesis•Cell walls made of cellulose

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Kingdom Animalia

•Multicellular• Ingestive

heterotrophs (consume food & digest it inside their bodies)

•Feed on plants or animals

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• Broadest, most inclusive taxon

Three domains:1.Archaea2.Eubacteria are unicellular

prokaryotes (no nucleus or membrane-bound organelles)

3.Eukarya are more complex and have a nucleus and membrane-bound organelles

Domains

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Domain Eukarya includes:•Protista (protozoans,

algae…)•Fungi (mushrooms,

yeasts …)•Plantae (multicellular

plants)•Animalia (multicellular

animals)

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Skills Practice1. List the levels of classification

from most broad to most specific.2. What type of organisms are

found in the kingdom Archaebacteria? Are these organisms unicellular or multicellular?

3. What 4 kingdoms are in the Domain Eukarya?

4. What is the difference between an autotroph and a heterotroph? Give an example of each.

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Classification is based on evolutionary relationships: •Homologous structures

(same structure, different function)

•Similar embryo development

•Similarity in DNA, RNA, or amino acid sequence of Proteins

30Homologous Structures show Similarities in

mammals.

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Similarities in Vertebrate Embryos

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• Phylogenetics- the analysis of the evolutionary

or ancestral relationships among a taxon (group).

• Phylogenetic diagram (tree)- a branching tree

that indicates how closely related species are.

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CladogramDiagram showing how organisms are

related based on shared, derived characteristics such as feathers, hair, or scales

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Primate Cladogram

Let’s Create A Cladogram from the following:

Derived Characterssegmente

d jaws hair placenta multicellula

r limbs

kangaroo + + + - + +

earthworm

+ - - - + -

amoeba - - - - - -

lizard + + - - + +

cat + + + + + + sponge - - - - + -

salmon + + - - + -

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Dichotomous Keying•Used to identify

organisms•Characteristics given in

pairs•Read both

characteristics and either go to another set of characteristics OR identify the organism

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Example of Dichotomous Key

1a Tentacles present – Go to 21b Tentacles absent – Go to 32a Eight Tentacles – Octopus2b More than 8 tentacles – 33a Tentacles hang down – go to 43b Tentacles upright–Sea Anemone4a Balloon-shaped body–Jellyfish4b Body NOT balloon-shaped - 5

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