1.2 Science of Classification

• Dichotomous Keys: Used to help identify organisms.
• Dichotomous keys are a series of questions about how an organism looks (morphology) to help identify it.
• Taxonomy: The science of naming, identifying and classifying species.
• Taxonomy organizes species into groups based on relatedness. Helps scientists better understand how species are related.
• Carolus Linnaeus lived before our modern understanding of genetics and evolution. He categorized organisms based on Morphology (how they looked). Developed binomial nomenclature naming system.
• Binomial Nomenclature: A system of naming organisms that uses the genus and species name.
• Italicized or underlined, Genus name is with a capital letter and species name is with a lower case letter. (ex. Escherichia coli becomes E. coli/Homo sapiens becomes H. sapiens).
• Not all organisms belong to the same genus so different species are grouped into separate categories. There are seven main groups (taxa).
• Phylogeny: The evolutionary development of a group of organisms.
• Phylogenetic Tree: Diagram that illustrates the evolutionary relationships between species.
• Taxa: A group of related organisms.
• Common Ancestor: An ancestor shared by two or more species.
• Domain: The broadest category of life.
• Domain consists of three large groups...

  1. Bacteria
  2. Archaea
  3. Eukarya
• Bacteria:

  • Prokaryotic
  • Single Celled
  • Cell walls with peptidoglycan (sugar)
  • Autotrophic/ Heterotrophic
  • No membrane bound nucleus
• Archaea:

  • Prokaryotic
  • Single Celled
  • Cell walls without Peptidoglycan
  • Autotrophic/ Heterotrophic
  • No membrane bound nucleus
  • Very Similar to Bacteria
  • Pyrococcus furiosa and Thermoproteus are hyperthermophiles
• Eukarya:

  • Eukaryotic
  • Single or Multicellular
  • Membrane bound nucleus
  • Split into FOUR major kingdoms:

  1. Protista
  2. Fungi
  3. Plantae
  4. Animalia
• Protists are a collection of oddball organisms and are not a true group.
• Protista:

  • Cell walls of Cellulose
  • Mostly single celled (unicellular); colonial and multicellular
  • Heterotrophic/ Autotrophic
  • Can be Animal, plant or fungus -like (ex. Amoeba/Paramecium)
• Fungi:

  • Cell walls of Chitin
  • Mostly multicellular; can be unicellular
  • Breaks down organic matter into nutrients
• Plantae:

  • Cell walls of Cellulose
  • Contain Chloroplasts (Photosynthetic organelles)
  • Mostly multicellular; unicellular
  • Autotrophic
  • Mosses, Ferns, Flowering Plants etc.
• Animalia:

  • Cell Membrane (No cell walls/ No Chloroplasts)
  • Multicellular
  • Heterotrophic
  • Birds, Fish, Reptiles, Mammals, Insects etc.