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Unit 11: Classification INSTRUCTIONS FOR NOTETAKING: Copy all words unless otherwise indicated. • Copy no tables or diagrams unless otherwise indicated. • Use Cornell (2-column style) format. • Leave room after each EQ for a 3 sentence summary. video use later • Essential Question #1: How and why are organisms classified the way they are? (Include HIERARCHY and EVOLUTIONARY RELATIONSHIPS.) How Are Organisms Classified? Organisms can be classified in one of two ways: 1. Based on P________ similarities 2. Based on E_________ relationships. This is a pangolin, native to Africa & Asia. They are mammals! Classification Method #1: Based on physical similarities • Taxonomy is the science of naming and classifying organisms. • Linnaeus developed the S______ naming system based on physical similarities, still used today. White oak: Quercus alba Classification Method #1: Based on physical similarities • Binomial nomenclature is a T___-part scientific naming system Linnaeus developed – uses Latin words – always written in italics – two parts are the genus name and species descriptor (always capitalized) (never capitalized) Example: Homo sapiens Classification Method #1: Based on physical similarities • Genus name- S____ in the same genus are thought to be closely related. • Scientific names help scientists to communicate. – Some species have very similar common names. – Some species have many common names. Classification Method #1: Based on physical similarities Linnaeus’ classification system has S_____ levels. • Each level is included in the level above it. • Levels get increasingly specific from kingdom to species. • (Copy the categories -blue tabs) Classification Method #1: Based on physical similarities The Linnaean classification system has limitations. • Linnaeus taxonomy doesn’t account for M_____ (DNA) evidence. – The technology didn’t exist during Linneaus’ time. – based only on physical similarities. Is there a more ACCURATE way of determining relationships between organisms? • Physical similarities are not always the result of C____ relationships. • G_____ similarities more accurately show evolutionary relationships. Classification Method #2:Based on Evolutionary Relationships M_____ classification is based on evolutionary relationships. (which relies on DNA evidence!) Classification Method #2:Based on Evolutionary Relationships • We make evolutionary trees to show relationships – evidence from living species, F____ record, and molecular data – shown with branching tree diagrams or “CLADOGRAMS” Classification Method #2:Based on Evolutionary Relationships – A clade is a group of species that shares a C____ ancestor. – Each species in a clade shares some traits with the ancestor. – Each species in a clade has traits that have changed. Classification Method #2:Based on Evolutionary Relationships • Derived characteristics are T____ shared in different degrees by clade members. 1 Tetrapoda clade – more closely related species share more derived characters 2 Amniota clade 3 Reptilia clade 4 Diapsida clade 5 Archosauria clade FEATHERS & TOOTHLESS BEAKS. – represented on cladogram as hash marks SKULL OPENINGS IN FRONT OF THE EYE & IN THE JAW OPENING IN THE SIDE OF THE SKULL SKULL OPENINGS BEHIND THE EYE EMBRYO PROTECTED BY AMNIOTIC FLUID FOUR LIMBS WITH DIGITS DERIVED CHARACTER Classification Method #2:Based on Evolutionary Relationships CLADE • Nodes represent the most recent common A____ of a clade. 1 Tetrapoda clade 2 Amniota clade 3 Reptilia clade 4 Diapsida clade 5 Archosauria clade FEATHERS AND TOOTHLESS BEAKS. SKULL OPENINGS IN FRONT OF THE EYE AND IN THE JAW • Clades can be identified by snipping a branch under a node. OPENING IN THE SIDE OF THE SKULL SKULL OPENINGS BEHIND THE EYE EMBRYO PROTECTED BY AMNIOTIC FLUID NODE FOUR LIMBS WITH DIGITS DERIVED CHARACTER • Essential Question #2: Why has the way we classify organisms changed over time? Classification Method #2: Based on Evolutionary Relationships Molecular evidence reveals species’ relatedness. • Molecular data may confirm classification based on physical similarities. • Molecular data may lead scientists to propose a N___ classification. • DNA is usually given the last word by scientists. Classification Method #2: Based on Evolutionary Relationships Molecular clocks provide clues to evolutionary history. Molecular clocks use M___ to estimate evolutionary time. • Mutations add up at a constant rate in related species. – This rate is the ticking of the molecular clock. – As more time passes, there will be more mutations. Mutations add up at a fairly constant rate in the DNA of species that evolved from a common ancestor. DNA sequence from a hypothetical ancestor Ten million years later— one mutation in each lineage Another ten million years later— one more mutation in each lineage The DNA sequences from two descendant species show mutations that have accumulated (black). The mutation rate of this sequence equals one mutation per ten million years. Classification Method #2: Based on Evolutionary Relationships • Scientists estimate mutation rates by linking molecular data and the F___ appearance of a species in fossil record. Notice how scientists compare various data sources (amino acids, fossils) to better understand relationships. It is helpful to have more than 1 source of information! • Essential Question #3: What are the distinguishing characteristics of the DOMAINS and KINGDOMS of living organisms? Recognize distinguishing characteristics of organisms (prokaryotic vs eukaryotic, unicellular vs multicellular, autotrophs vs heterotrophs, environments) Classification Groups • Domain, Kingdom, Phylum, Class, Order, Family, Genus, species • 20 Classification Groups •There is a hierarchy of groups (taxa) from broadest to most specific • Domain BROADEST TAXON • Kingdom • Phylum (Division – used for plants) • Class • Order • Family • Genus Most Specific • Species 21 • Dumb • King • Phillip • Came • Over • For • Gooseberry • Soup! 22 READ, BUT DON’T COPY 23 The “Tree of Life”: Domains & Kingdoms The current tree of life has three domains. The three domains in the tree of life are B_____, Archaea, and Eukarya. – domain model more clearly shows P_____ diversity The “Tree of Life”: Domains & Kingdoms Kingdoms are smaller groups “under” domains Classification is always a work in progress. • The tree of life shows our most current understanding. • New discoveries can lead to changes in classification. – Until 1866: only two kingdoms: A____ and P_____ The “Tree of Life”: Domains & Kingdoms Classification is always a work in progress. – 1866: all single-celled organisms moved to kingdom Protista Plantae Animalia Protista – 1938: prokaryotes moved to kingdom Monera Archea – 1959: F_____ moved to own kingdom Fungi Bacteria – 1977: kingdom Monera split into kingdoms Bacteria and Archaea The “Tree of Life”: Domains & Kingdoms READ, BUT DON’T COPY Kingdoms Archaea and Bacteria Archaea Bacteria Organization Unicellular Unicellular Where Found Harsh Environments (sewers, hot springs, geysers) All habitats, except harsh ex: stomach of animals Functions Develop medicines Decomposers in environment, used commercially (cheese, medicine) Cell Wall Not peptidoglycan Peptidoglycan Obtain Food Absorption, Photosynthesis chemosynthesis Absorption, Photosynthesis chemosynthesis Motility Some are able to move Some are able to move READ, BUT DON’T COPY 28 Binomial Nomenclature Which TWO are more closely related? copyright cmassengale 29