Classifications of Organisms Flashcards
Levels of Classification (hierarchal divisions)
- Kingdom (microbiologists use domains)
- Phylum
- Class
- Order
- Family
- Genus
- Species
Domains include…
Archaea, Eubacteria and Eukarya.
Kingdoms include…
Archaeabacteria, Eubacteria, Animalia, Plantae, Protista and Fungi.
Progenote
- The last universal ancestor (LUCA)
- Most universal ancestor for all organisms living on earth at this moment.
- Organisms derived from this are then grouped into 3 domains/6 kingdoms
Species
- Taxonomic unit that represents a specific type of organism that can interbreed.
- These organisms must be able to reproduce sexually.
- Cannot be applied to bacteria (lack ability to reproduce sexually)
Do all MICROorganisms reproduce asexually (i.e. binary fission)?
Nope.
Although most bacteria/archaea reproduce via binary fission, some of these organisms exchange their genetic information via recombination.
Do all MACROorganisms reproduce sexually?
Nope.
Sexual reproduction is quite rare in some species but for the most part, animals do perform sexual reproduction.
How are species identified?
Comparisons with known standard reference strains.
Species (Microbiologist definition)
Set of strains that share significant characteristics and are different from other sets of strains.
Strain
Population that results in unique individuals or pure cultures
i. e. different strains are just subtypes of a specific species (genetic variations)
ex. different races = different strains from the same species.
Biotypes
Strains with biochemical/physiological differences.
Morphotypes
Strains with morphological differences
Serotypes
Strains with antigenic differences.
Pathotypes
Disease-causing strain
Properties of organisms used for classification
- Colony morphology
- Cell shape and grouping
- Structure of cell wall (can be determined via gram stain)
- Cell structures
- Biochemical/metabolic characteristics
- Serological testing
- Molecular properties
Serological testing + its advantages
- Uses antiserums (antibodies) specific against a group of microorganisms (aka their antigens)
- Very specific
- Doesn’t require pure cultures so we can identify microorganisms that cannot be grown in labs.
Characteristics of molecular properties
- G + C contents
- Nucleic acid hybridization (dsDNA)
- Nucleic acid sequencing.
- *more in notes
Eubacteria classification:
- Shape
- Oxygen requirements
- Diseases they cause
What kind of energy do Eubacteria produce?
- Photosynthesis or Chemosynthesis from organic compounds
Proteobacteria;
Domain, cell wall, membranes, energy
- Eubacteria
- Peptidoglycan cell wall
- 2 membranes
- Obtains energy via chemosynthesis or photosynthesis
Photosynthetic Bacteria
- Cyanobacteria (sulfur) and some Proteobacteria (Non sulfur).
- These bacteria are pigmented with green and purple colors.
Bacteroids;
Domain, cell membrane composition, environment + what type of pathogens are they?, oxygen requirements
- Eubacteria
- 1 sphingolipid (rare) membrane
- Do not tolerate O2… found in intestines.
- Opportunistic pathogens;
- Mutualistic organisms!
Gram Positive Bacteria;
Domain, cell wall, cell membrane, shapes, energy.
- Eubacteria
- Peptidoglycan cell wall
- only ONE membrane
- Usually spheres or rods
- Chemosynthesis from organic compounds
- ALSO makes spores.
Gram Negative Bacteria; Domain, cell wall, cell membrane
- Eubacteria
- Peptidoglycan cell wall
- TWO membranes (one outside one inside cell wall)
