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Classifications
 

Classifications

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    Classifications Classifications Presentation Transcript

    • Taxonomy, Kingdoms, Classifications
    • • To study the diversity of life, biologists use a classification system to name organisms and group them in a logical manner• Binomial nomenclature: two part scientific name: first part is the genus (closely related species) – second part is name unique to the species• Ex: Ursus maritimus
    • Carolus Linnaeus (1707-1778)• Hierarchical system of classification with 7 levels: ordered from smallest to largest• Species, genus, family, order, class, phylum, and kingdom (animalia, plantae)• Organisms were grouped based on visible similarities and differences
    • Evolutionary classification• Phylogeny – evolutionary relationships among organisms (Darwin)• Organisms are grouped into catagories that represent lines of evolutionary descent and not just physical similarities (evolutionary classification)• Derived characters; appear in recent lineage but not in older member
    • Cont.• Derived characters can be used to construct a cladogram, a diagram that shows the evolutionary relationships among a group of organisms
    • DNA and RNA• Genes of many organisms show important similarities at the molecular level. Similarities in DNA can be used to help determine classification and evolutionary relationships• Molecular clock – uses DNA comparisons to estimate the time that two species have been evolving independently
    • Kingdoms• First - Animalia and plantae• Additional – Monera (split into Eubacteria and Archaebacteria), Protista, Fungi,• Current classification has the above 6 kingdoms• Domain – 3 categories (larger than kingdom)• Bacteria• Archaea• Eukarya
    • Domains 3 categories (larger than kingdom)• Bacteria – unicellular, prokaryotic• Archaea – extremophiles• Eukarya – all organisms that have a nucleus
    • Protist:• Protista – means “very first” 1.5 billion• Margulis – evolved from mitochondria and chloroplasts found in eukaryotic cells may have descended from aerobic and photosynthetic prokaryotes that began to live inside larger cells• Protista - Eukaryotes that do not belong to plantae, animalia, fungi or a prokaryote
    • Cont.• Has nucleus and membrane-bound organelles• Most unicellular• Animallike: heterotrophs,• Plantlike: autotrophs• Funguslike: decomposers
    • Fungi• Heterotrophs• Absorb nutrients (hyphae/mycelium)• Have cell walls (chitin)• Reproduced with fruiting body• Asexually – hyphae break off and grow or spore production• Two mating types (+) and (-) meet, fuse, diploid zygote enters meiosis and completes reproduction.
    • Plantae• Multicellular eukaryotes that have cell walls made of cellulose, carry out photosynthesis (trees, shrubs, grasses, mosses, ferns)• Life cycle has 2 alternating phases:• Diploid (2N) – sporophyte (spore producting)• Haploid (N) – gametophyte (gamete producing)
    • Survival• Sunlight• Water and minerals• Gas exchange• Transport of water and nutrients• Evolved from early multicellular green algae
    • Animalia• Multicellular, eukaryotic heterotrophs lack cell walls• Invertebrates – no back bone (squid, sea stars, microrganisms)• Vertebrates – with back bones (humans, reptiles, birds, mammals)
    • Survival• Homeostasis – stable state maintained by feedback mechanisms• Feedback inhibition – product or results stops process or limits the process• Feeding - nutrients• Respiration – transport of gases (O2 and CO2)• Circulation – movement of material in organism
    • Cont.• Excretion – removal of waste products• Response – nervous systems (stimuli)• Movement – muscle or muscle-like tissue that allows for mobility• Reproduction – production of offspring (usually through sexual reproduction)
    • Animal evolution• Complex animals tend to have high levels of cell specialization and internal body organization, bilateral body symmetry, front end or head with sense organs (cephalization), and body cavity• Cell → tissue → organs → organ systems
    • Sponges• ancient animals• Multicellular, heterotrophs, with some specialized cells, asymmetrical• Movement of water through a central cavity provides a simple mechanism for feeding (filtering), respiration, circulation, excretion
    • Cnidaria• Soft-bodied, carnivorous animals with stinging tentacles arranged in circles around their mouths, simplest animals to have body symmetry and specialized tissues• Life cycle: polyp and medusa• Jellies, hydras, anemones,