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,