2. The Tree of Life Chapter 26

3. 2 Why classify organisms? 1.Order and organization 2.Common names confusing Ex. Jellyfish, starfish, etc. 3.Common names vary from place to place Ex. Cougar, puma, mountain lion

4. 3 Aristotle divided organisms into two groups: Plants Animals 1.)herbs1.)air 2.)shrubs2.)sea 3.)trees3.)land

5. 4 Linneaus: founder of modern taxonomy Classified organisms based on structural features Binomial Nomenclature: each species is given a two-word Latin name 1st word = genus 2nd word = species Ex: canis familiaris felis domesticus homo sapiens

6. 5 The Linnaean Hierarchy Taxa are based on shared characteristics -Domain (most shared) -Kingdom -Phylum -Class -Order -Family -Genus -Species (least shared)

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9. 8 Classification of Organisms Taxonomy: the science of classifying living things -A classification level is called a taxon - taxonomic key: used to identify species, by following a series of choices between characteristics

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11. 10 Grouping Organisms 3 domains: -Bacteria -Archaea -Eukarya Archaea and Eukarya are more closely related to each other than to bacteria

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13. 12 Domain: Bacteria kingdom: Eubacteria Unicellular Prokaryotic, Cell walls with peptidoglycan Some heterotrophic, some autotrophic Most abundant organisms on Earth Ex: E. coli, Streptococcus, many diseases

14. 13 Domain: Archaea kingdom: archaebacteria Unicellular Prokaryotic, Cell walls lack peptidoglycan Most heterotrophic, some autotrophs Includes methanogens, extremophiles

15. 14 Eukarya Eukaryotes appeared about 2.5 BYA Key characteristics: –Complex cell organization –Multicellular –Sexual reproduction

16. 15 Mitochondria and chloroplasts most likely gained entry by endosymbiosis -Mitochondria were derived from purple nonsulfur bacteria -Chloroplasts from cyanobacteria

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18. 17 Eukaryote Kingdoms 1.Protista Unicellular (some multi) Most are heterotrophic Ex: simple algae, giant kelp, amoeba, paramecium (Catchall for eukaryotes that are not plant, fungus or animal)

19. 18 2.Fungi Multicellular (some uni) Heterotrophic by absorption Ex: yeast, mold, mushrooms, athlete’s foot

20. 19 3.Plants Multicellular Autotrophic Ex: trees, ferns, tulips, some algae

21. 20 Land plants arose from an ancestral green alga, and only once during evolution

22. 21 4.Animals Multicellular Heterotrophic by ingestion Ex: insects, worms, vertebrates

23. 22 Molecular systematics is leading to a revision of evolutionary relationships among animals

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26. 25 Viruses Are not organisms and so cannot be placed in any of the kingdoms Are literally “parasitic” chemicals -DNA or RNA wrapped in protein Can only reproduce within living cells Vary greatly in appearance and size