classification and identification


study of organisms to arrange them into groups for purposes of classification and identification
identify a particular unknown (one organism)
who is related to who (family tree)
prokaryotic species
a group of genetically related cells with the same core genetics
taxonomic hierarchy

  • domain
  • kingdom (eukaryotes only)
  • phylum or division
  • class
  • order
  • family
  • genus (more broad)
  • species (+/- strains) 

Three domain classification sysytem
Bacteria, Archaea, Eukarya

where did all cells arise from?


prokaryotic ancestor
appearance and functioning

microscopic morphology


  • size and shape
  • gram and special stain 

colony morphology


  • unique appearance, pigments
  • may require differential media

metabolic testing


  • enzymes
  • groups of enzymes in pathways

dichotomous key
lays out the test and helps one walk through the different test with their results to narrow down to one thing
has chambers of media and innoculates everything at once
Steps of phenotype

  • microscopic morphology
  • colony morphology
  • metabolic testing
  • serology
  • other analyses

2 ways for identification of prokaryotes



steps of genotype

  • sequencing rRNA/rDNA
  • DNA fingerprinting (RFLP, PCR)
  • DNA probes (colony blotting, FISH, DNA microarray)

why is rRNA preferred?
it doesnt change over time because it is ribosomal. it is conserved.
Categories: Microbiology