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Ch 18- Classification

Ch 18- Classification. Why do biologists organize living organisms into groups that have biological meaning? Study the diversity of life Use classification system to name organisms and group them in logical manner

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Ch 18- Classification

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  1. Ch 18- Classification • Why do biologists organize living organisms into groups that have biological meaning? • Study the diversity of life • Use classification system to name organisms and group them in logical manner • Taxonomy- discipline of classifying organisms and assigning each organism a universally accepted name

  2. Scientific Names • Why don’t scientists use common names? • Use Latin and Greek • Bionomial nomenclature- two word naming system • Each species given two-part scientific name • Carolus Linnaeus • First word is capitalized, second word is lowercased, written in italics • Ursusarctos- grizzly bear • Ursus- genus to which organism belongs • Genus- group of closely related species • artos- unique to each species within the genus

  3. Linnaeus’s System of Classification • Linnaeus’s hierarchical system of classification uses seven taxonomic categories • Species • Genus • Family • Order • Class • Phylum • Kingdom • Taxon- taxonomic category • Family- genera that share many characteristics • Ursidae • Order- broad taxonomic category composed of similar families • Carnivora • Class- composed of similar orders • Mammalia • Phylum- several classes that share important characteristics • Chordata • Kingdom- largest and most inclusive categories • Animalia

  4. Sec 2- Modern Evolutionary Classification • Phylogeny- evolutionary relationships among organisms • How are evolutionary relationships important in classification? • Organisms are grouped into categories that represent lines of evolutionary descent, or phylogeny- not just physical similarities • Evolutionary classification- grouping organisms together based on their evolutionary history

  5. Classification Using Cladograms • Cladistic analysis identifies new characteristics that arise as lineages evolve over time • Derived characters- characteristics that appear in recent parts of a lineage but not in its older members • Evolutionary innovation, or new characteristics • Cladogram- diagram that shows evolutionary relationships among group of organisms • Help understand how one lineage branched from another • Use derived characters

  6. Similarities in DNA and RNA • All organisms use DNA and RNA to pass on information • How can DNA and RNA help scientists determine evolutionary relationships? • Genes of many organisms show important similarities at molecular level • Can be used to determine classification and evolutionary relationships • Similar genes • Human muscles and yeast • DNA evidence • More similar DNA sequence of two species, the more recently they shared a common ancestor • American vulture, African vulture, stork

  7. Molecular Clocks • Uses DNA comparisons to estimate the length of time that two species have been evolving independently • Relies on mutations • Comparison between DNA sequences can reveal how dissimilar the genes are- indicates how long ago two species shared a common ancestor

  8. Sec 3- Kingdoms and Domains • How many kingdoms of life are there? • What are the 6 kingdoms? • Eubacteria • Archaebacteria • Protista • Fungi • Plantae • Animalia • Domain- taxonomic category larger than kingdom • Eukarya- composed of protists, fungi, plants, animals • Bacteria- Eubacteria • Archaea- Archaebacteria

  9. Domain Bacteria and Archaea • Bacteria- unicellular and prokaryotic • Thick, rigid cell walls • Ecologically diverse- free living to deadly parasites • Some photosynthetic, some not • Some depend on oxygen, some not • Archaea- unicellular and prokaryotic • Most extreme environments • Many survive only in absence of oxygen • Cell walls lack peptidoglycan • Unusual lipids in cell membranes, not found in any other organism

  10. Domain Eukarya • All have nucleus • Protista, Fungi, Plantae, Animalia • Protista- display greatest variety • Unicellular and multicellular • Photosynthetic and heterotrophic • Fungi- heterotrophs • Feed on dead or decaying organic matter • Unicellular or multicellular • Plantae- multicellular organisms that are photosynthetic autotrophs • Animalia- multicellular and heterotrophic • Incredible diversity

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