Week 1

• Taxonomists


  Biologists who classify organisms
• Taxonomy


  The study of identifying, naming, and classifying living things in relation to other living things
• Systematics


  The study of the kinds and diversity of organisms and of all relationships among them
• Systematists


  Use data ranging from fossils to molecules and genes to infer evolutionary relationships. This information is used to construct the phylogenetic tree of life.
• Organisms can be classified according to any number of criteria, including overall similarities, colors, ecological functions, and others
• Organisms that ever existed on this planet are related to other organisms in a branching evolutionary pattern called the tree of life
• Tree thinking or phylogenetic thinking

  Helps us unknot the branching evolutionary relationships between surviving or extant species, while thinking about the passage of time and the ancestors of each of those living species
• Three Domain System


  A system for classifying biological organisms that is developed by Carl Woese in 1990
• The current Three Domain System groups organisms primarily based on differences in ribosomal RNA (rRNA) structure
• Ribosomal RNA

  A molecular building block for ribosomes
• It is generally thought that all cells came from a common ancestor cell termed the last universal common ancestor (LUCA)
• What are the three domains?

  • Archaea
  • Bacteria
  • Eukarya
• Kingdoms


  • Archaebacteria (ancient bacteria)
  • Eubacteria (true bacteria)
  • Protista
  • Fungi
  • Plantae
  • Animalia
• Archaea


  Contains single-celled organisms
• Archaea

  • Have genes that are like both bacteria and eukaryotes
  • Are prokaryotic organisms and do not have a membrane-bound nucleus. They lack internal cell organelles, and many are about the same size as and similar in shape to bacteria
• Archaea and bacteria difference

  Different cell wall composition, membrane composition, rRNA type
• Archaea

  • Extreme organisms that live under some of the most extreme environmental conditions
• Archaea's 3 main phyla

  • Crenarchaeota
  • Euryarchaeota
  • Korarchaeota
• Crenarchaeota


  Include many organisms that are hyperthermophiles and thermoacidophiles
• Hyperthermophiles


  Archaea that thrive in environments with great temperature extremes
• Thermoacidophiles


  Archaea that thrive in extremely hot and acidic environments
• Methanogens


  Archaea of the Euryarchaeota phylum
• Little is known about Korarchaeota archaea as few species have been found living in places such as hot springs, hydrothermal vents, and obsidian pools
• Bacteria

  • They are generally feared because some are pathogenic
  • They perform vital functions, such as enabling us to properly digest and absorb nutrients from the foods we eat
  • They are important for the recycling of nutrients in the global ecosystem as they are primary decomposers
  • They have unique cell wall composition and rRNA type
• Five Categories of Bacteria Domain

  • Proteobacteria
  • Cyanobacteria
  • Firmicutes
  • Chlamydiae
  • Spirochetes
• Proteobacteria


  This phylum contains the largest group of bacteria
• Proteobacteria


  • E.coli
  • Salmonella
  • Heliobacter pylori
  • Vibrio bacteria
• Cyanobacteria


  These bacteria are capable of photosynthesis. They are also known as blue-green algae
• Firmicutes


  These are gram-positive bacteria
• Firmicutes


  • Clostridium
  • Bacillus
  • Mycoplasmas (bacteria without cell walls)
• Chlamydiae


  These parasitic bacteria reproduce inside their host's cells
• Spirochetes


  These corkscrew-shaped bacteria exhibit a unique twisting motion
• Spirochetes


  • Borrelia burgdorferi
  • Treponema pallidum
• Eukarya domain


  Includes eukaryotes or organisms that have a membrane-bound nucleus
• Eukaryotes have rRNA that is distinct from bacteria and archaean's
• Plant and fungi organisms contain cell walls that are different in composition than bacteria
• Eukaryotic cells are typically resistant to antibacterial antibiotics
• Organisms in Eukarya domain

  • Protists
  • Fungi
  • Plants
  • Animals
• Phylogenetic tree


  A hypothetical visual representation of the relationship between different organisms, showing the path through evolutionary time from a common ancestor to different descendants
• Phylogenetic Trees


  • Intended to show patterns of descent, not phenotypic similarity
  • Sequence of branching does not necessarily indicate the actual (absolute) ages of the species
  • Do not assume that a taxon evolved from the taxon next to it