classifications
DESCRIPTION
TRANSCRIPT
• 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