Presentation on theme: "Georgia Performance Standards:"— Presentation transcript:
1 Georgia Performance Standards: Classification:Georgia Performance Standards:Compare how structures and functions vary between the six kingdoms (archaebacteria, eubacteria, protests, fungi, plants, and animals).Examine the evolutionary basis of modern classification systemsEssential Questions:How does the evidence of evolution contribute to modern classification systems?Why classify?3. On what criteria do Taxonomists base their classification of organisms?4. In what way does scientific discovery lead to the development of a new classification group?
2 Why Classify?To study the diversity of life, biologists use a classification system to name organisms and group them in a logical manner.In taxonomy, scientists classify organisms and assign each organism a universally accepted name.By using a scientific name, biologists can be certain that everyone is discussing the same organism.
3 Early Efforts at Naming Organisms The first attempts at standard scientific names often described the physical characteristics of a species in great detail.Results in long namesDifficult to standardize the names of organismsDifferent scientists described different characteristics.
4 Binomial Nomenclature Carolus Linnaeus developed a two-word naming system called binomial nomenclature.In binomial nomenclature, each species is assigned a two-part scientific name.The scientific name is always written in italics.The first word (the genus) is capitalizedThe second word (the species) is lowercased.
5 Linnaeus's System of Classification A group or level of organization is called a taxonomic category, or taxonThe are 7 taxonomic categories. (from smallest to largest)speciesgenusfamilyorderclassPhylumkingdom.
6 The 7 taxonomic categories Species - a group of organisms that breed with one another and produce fertile offspring.Genus - a group of closely related species.Family - genera that share many characteristics.Order - is a broad taxonomic category composed of similar families.Class - is composed of similar orders.Phylum- several different classes that share important characteristics.Kingdom - largest taxonomic group, consisting of closely related phyla
8 Checkpoint Questions: 1. How are living things organized for study?2. Describe the system for naming species that Linnaeus developed.3. What are the seven taxonomic categories of Linnaeus’s classification system?4. Why do scientists avoid using common names when discussing organisms?5. Which category has more biological meaning—all brown birds or all hawklike birds? Why?
9 Modern Evolutionary Classification Organisms are grouped into categories that represent lines of evolutionary descent, not just physical similaritiesThis strategy of grouping organisms together based on their evolutionary history is called evolutionary classification.Modern classification systems are based upon biochemical and genetic evidence that indicates evolutionary relationships
10 Classification Using Cladograms Cladistic analysis identifies and considers only the characteristics that arise as lineages evolve over time.Characteristics that appear in recent parts of a lineage but not in its older members are called derived characters.Derived characters can be used to construct a cladogram, a diagram that shows the evolutionary relationships among a group of organisms.
11 Traditional Classification Versus Cladogram TRADITIONAL CLASSIFICATION Section 18-2AppendagesConical ShellsCrustaceansGastropodCrabBarnacleLimpetCrabBarnacleLimpetMolted exoskeletonSegmentationTiny free-swimming larvaTRADITIONAL CLASSIFICATIONCLADOGRAMGo to Section:
12 Modern Evolutionary Classification Similarities in DNA and RNAThe genes of many organisms show important similarities at the molecular level that can be used as criteria to help determine classification.
13 Modern Evolutionary Classification Molecular ClocksComparisons of DNA can also be used to mark the passage of evolutionary time.A model known as a molecular clock uses DNA comparisons to estimate the length of time that two species have been evolving independently.Comparison reveals more DNA in common, the more recent the common ancestor
14 Checkpoint Questions: How is information about evolutionary relationships useful in classification?How are genes used to help scientists classify organisms?3. What is the principle behind cladistic analysis?4. Describe the relationship between evolutionary time and the similarity of genes in two species.5. How have new discoveries in molecular biology affected the way in which we classify organisms compared with the system used by Linnaeus? Constructing a Chart
15 Kingdoms and Domains The six-kingdom system of classification includes the following kingdoms:EubacteriaArchaebacteriaProtistaFungiPlantaeAnimalia.
16 The Three-Domain System The domain is the most inclusive taxonomic category; larger than a kingdom The three domains are:Bacteria : kingdom EubacteriaArchaea,: kingdom Archaebacteria;Eukarya :Kingdom protists, fungi, plants, and animals.
17 Cladogram of Six Kingdoms and Three Domains Section 18-3DOMAIN ARCHAEADOMAIN EUKARYAKingdomsEubacteriaArchaebacteriaProtistaPlantaeFungiAnimaliaDOMAIN BACTERIAGo to Section:
18 Classification of Living Things Key Characteristics of Kingdoms and DomainsClassification of Living ThingsEukaryaDOMAINKINGDOMCELL TYPECELL STRUCTURESNUMBER OF CELLSMODE OF NUTRITIONEXAMPLESBacteriaEubacteriaProkaryoteCell walls with peptidoglycanUnicellularAutotroph or heterotrophStreptococcus, Escherichia coliArchaeaArchaebacteriaProkaryoteCell walls without peptidoglycanUnicellularAutotroph or heterotrophMethanogens, halophilesProtistaEukaryoteCell walls of cellulose in some; some have chloroplastsMost unicellular; some colonial; some multicellularAutotroph or heterotrophAmoeba, Paramecium, slime molds, giant kelpPlantaeEukaryoteCell walls of cellulose; chloroplastsMulticellularAutotrophMosses, ferns, flowering plantsFungiEukaryoteCell walls of chitinMost multicellular; some unicellularHeterotrophMushrooms, yeastsAnimaliaEukaryoteNo cell walls or chloroplastsMulticellularHeterotrophSponges, worms, insects, fishes, mammalsGo to Section:
19 Section 18-3 Living Things Eukaryotic cellsProkaryotic cellsare characterized byImportant characteristicsand differingwhich place them inDomain EukaryaCell wall structuressuch aswhich is subdivided intowhich place them inKingdom PlantaeKingdom ProtistaKingdom FungiKingdom AnimaliaDomain BacteriaDomain Archaeawhich coincides withwhich coincides withKingdom EubacteriaKingdom ArchaebacteriaGo to Section:
20 Checkpoint Questions: What are the six kingdoms of life as they are now identified? What are the three domains of life?3. Why was the kingdom Monera divided into two separate kingdoms?4. Why might kingdom Protista be thought of as the “odds and ends” kingdom?5. Which kingdoms include only prokaryotes? Which kingdoms include only heterotrophs?