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Chapter 18: Classification

Chapter 18: Classification. 18-1: History of Taxonomy . Early Systems of Classification. Taxonomy: branch of biology that names and groups organisms according to their characteristics and evolutionary history. Aristotle . 2,000 years ago Plants: three categories based on their stems

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Chapter 18: Classification

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  1. Chapter 18:Classification

  2. 18-1: History of Taxonomy

  3. Early Systems of Classification • Taxonomy: branch of biology that names and groups organisms according to their characteristics and evolutionary history

  4. Aristotle • 2,000 years ago • Plants: three categories based on their stems • Animals: based on where they live • Land • Water • Air

  5. Problems • Scientific exploration  discover MANY new species • Common name did not describe actual animal • Ex: Jellyfish: NOT a fish • Common names varied by location

  6. Linnaeus’ System • Swedish naturalist, Carolus Linnaeus, (1707-78) • Used organisms morphology to categorize it • Form and structure

  7. Levels of Classification • Kingdom • Phylum • Class • Order • Family • Genus • Species Kings Play Chess On Funny Green Squares

  8. Binomial Nomenclature • Species name has two parts: • Genus • Species identifier: descriptive word • Ex: Homo sapien • Homo is the genus • sapien means “wise”

  9. Further Naming and Classifying • Botanists (plants) further classify • Varieties: subset of species • Subspecies: zoologists refer to species that occur in different geographic locations • Phylogeny: evolutionary history

  10. 18-2: Modern Phylogenetic Taxonomy • Past: • Morphology • Preset: • Morphology • Chromosomal characteristics • Nucleotide and amino acid sequences • Embryonic development

  11. Systematics • Organizes tremendous diversity of living things in the context of evolution • Phylogenetic tree: a family tree that shows the evolutionary relationships thought to exist among groups of organisms • Represents a hypothesis • Based on multiple lines of evidence • Subject to change

  12. The Fossil Record • Often provides clues to evolutionary relationships • HOWEVER: • Some fossil records very complete (ocean-living invertebrates) others are missing large portions

  13. Morphology • Compare morphology of organism to morphology of other living things • Homologous features show descent from common ancestors

  14. Embryonic Patterns of Development • Early on in development most living things look very similar • As they develop it is easier to see how their morphology differs

  15. Chromosomes and Macromolecules • DNA, RNA, and proteins • Number of amino acid differences is a clue to how long ago two species diverged from a shared ancestor • Problem: ASSUMES all changes to sequence occur at random and NOT natural selection

  16. Karyotype • Some similar bands on chromosomes, more related two organisms are

  17. Cladistics • Uses shared derived characters of organisms to establish evolutionary relationships • Derived characters: feature that apparently evolved only within the group under consideration • Cladograms:ancestry diagrams made by means of cladistical analysis

  18. 18-3:Two Modern Systems of Classification

  19. Six-Kingdom System • Archaebacteria • Eubacteria • Protista • Fungi • Plantae • Animalia

  20. Kingdom Archaebacteria • Unicellular prokaryotes • Distinctive cell membrane • Autotrophs: chemiosmosis (use elements/chemicals for energy)

  21. Many live in very harsh environments • Hot spring • VERY salty water • Anaerobic environments (No air) • Archae- in Greek means “ancient” • FIRST organisms on Earth • Reproduce: Binary fission • Nutrition: Autotrophs and heterotrophs

  22. Kingdom Eubacteria • Unicellular prokaryotes • Eu- means “true” • Most bacteria that affect your life • Tooth decay • Milk  yogurt • Food poisoning • Reproduce: Binary fission • Nutrition: Autotrophs and heterotrophs

  23. Kingdom Protista • Eukaryotic and prokaryotic • Difficult to describe • All eukaryotes that are not fungi, plants, or animals • Reproduction: sexual cycles unknown but they do exchange genetic info • Nutrition: Autotrophs AND heterotrophs • Euglena can photosynthesize • Amoeba eats other organisms

  24. Kingdom Fungi • Unicellular and multicellular eukaryotes • Reproduction: sexual cycles unknown but they do exchange genetic info • Nutrition: Heterotrophs; Absorb nutrients • Ex: puffballs, mushrooms, rusts, molds

  25. Kingdom Plantae • Multicellular plants • Reproduction: most have sexual cycle based on meiosis • Nutrition: All but a few are heterotrophic

  26. Kingdom Animalia • Multicellular • Eukaryotic • Reproduction: Sexual by means of meiosis forming gametes • Nutrition: Heterotrophs • Most have body symmetry and move about environment

  27. Three-Domain System • In 1977, molecular biologist, Carl Woese • Classified by comparing ribosomal RNA • Why? All organisms have ribosomes so we can look at every living thing’s rRNA and compare it with others • Three main domains: • Domain Archae • Domain Bacteria • Domain Eukarya

  28. Domain Archae • Same as the kingdom Archaebacteria (in six kingdom system)

  29. Domain Bacteria • Same as kingdom Eubacteria

  30. Domain Eukarya • Protists, fungi, plants, and animals • Have nuclei with linear chromosomes and membrane bound organelles

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