Thursday Notes

Taxonomy & Phylogeny

Taxonomy – the classification & naming of organisms

Phylogeny – evolutionary history of a group of organisms

5 – Kingdom Classification System

Developed by Robert Whittaker in 1969

  1. Monenra (bacteria) (No longer used)
  2. Protista (algae, protozoa, etc.) (No longer used)
  3. Fungi
  4. Plantae
  5. Animalia

Domain System – Developed by Carl Woes in 1978, based on similarities in rRNA

◊Note – There are no Kingdoms in Bacteria & Archaea (Prokaryotes)

Bacterial Species – population of cells w/ similar characteristics

Strains – sub-species ex. 0157-H7

Domain Archaea


  • Extreme halophiles (Halobacterium): Salt environments
  • Hyperthermophiles (pyrodictium): Hot environments
  • Acidophiles (sulfolobus): Acidic environments

Methanogens (Methanobacterium) → Methane generating archaea CH4

Domain Bacteria

Phylum Proteobacteria Characteristics:

  • Gram-Negative
  • Largest, most diverse group of bacteria
  • Proteo- meaning “many forms”


  • Alphaproteobacteria
  • Betaproteobacteria
  • Gammaproteobacteria
  • Deltaproteobacteria
  • Epsilonproteobacteria

Class: Alphaproteobacteria:

Rickettsia rickettsiiRocky Mountain Spotted Fever:

  • Obligate intracellular parasite
  • Transmitted by vector – tick (Dermacenter)
  • Infects endothelial cells, including those of capillaries & lyces cells which creates the red spots.
  • Symptoms: Fever, headache, chills, nausea & spotted non-itchy rash.

Orientia tsutsugamushi – Scrub typhys

  • Vector is chiggers (mites)
  • endemic to Eastern Asia, Australia, Western Pacific Islands
  • Symptoms – Muscle pain

Class: Betaproteobacteria

Neisseria gonorrhoeae – Gonorrhea”the clap” (term came from french word for brothel – Clapoir)

  • STD
  • Humans are only host/reservoir
  • Virulence Factors – fimbriae & capsules that cause the bacteria to adhere to mucous membranes of host.

Bordetella pertusis – Whooping Cough

  • Virulence factors – bacteria attached to lipids in cytoplasmic membranes of tracheal cells via adhesions such as pertussis toxin & hemagglutinin. This causes increased mucus production while paralyzing the cilia of tracheal cells. 
  • Survives in phagocytes & can travel to other parts of body.

Class: Gammaproteobacteria

Vibrio Cholerae – Cholera

  • Humans become infected by ingesting contaminated food or water
  • Virulence factor – causes secretion of water & electrolytes in host
  • Environment of human body causes toxins in genes to be expressed → toxins cause intestinal cells to secrete water & electrolytes.

Legionella pneumophila – Legionaire’s Disease

  • Got name from outbreak at American legion meeting in Philly in 1970
  • Common in water, including condensation in air conditioning units & water towers. Live inside protozoa in fresh water such as rivers.
  • Exposure route – Inhalation.

Haemophilus influenzae  – Meningitis, pneumoniae

  • Obligate intracellular parasite
  • colonizes mucus membranes
  • Capsules that evade phagocytes
  • Type B causes most problems in humans.

pseudomonas auruginosa –

  • Opportunistic pathogen, common in soil
  • green pigment

Francisella tularensis – tularemia

  • Capsules
  • intracellular parasite
  • reservoirs – rabbits, ticks
  • symptoms include buboes, dry cough

Yersina pestis – Plague

  • buboes (swollen lymph nodes)
  • vector – flea; reservoir – rodents
  • 2 types: Bubonic plague & pneumonic plague
  • 14th century it killed 1/3 of Europeans & mid 500s AD – late 1700s AD killed 40 million people.

Extra Notes

Virulence Factor Definition – characteristics of a pathogenic organism that causes harm to the host

Note – Archaea & Eukarya have histones (proteins associated w/ DNA) Bacteria do not.

Ex Credit:  Lichen – fungus & algae &/or cyanobacteria, crusty material found on branches or rocks.

3 Types of Symbiotic Relationships:

  1. Parasitic – one organism is harmed
  2. Commensalistic – one organism is neutral
  3. Mutualistic – both organisms benefit




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