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)
Pathogens + Spores = ?
FATAL
Atypical bacteria (list) + domain
- Chlamydia
- Mycoplasms
- Spirochetes
- Mycobacteria
Eubacteria
Chlamydia; cell wall, cell membrane, energy production
- Not based on peptidoglycan sugars
- 2 membranes (Gram negative)
- Obligate intracellular parasite + unable to generate energy…
Obligate intracellular parasite
Cannot reproduce without a host as they have high reliance on intracellular resources.
It also needs an energy source from the host.
Mycoplasms; cell wall, cell membrane, energy
- No cell wall = no defined shape
- Plasma membrane present
- Obligate intracellular parasite = unable to generate energy
Spirochetes; shape, diseases
- cork screw
- Syphilis + lime disease
Mycobacteria; Type of bacteria, cell wall, cell wall permeability, DNA + diseases
- Acid fast bacteria bc of impermeability to dyes etc
- mycolic acid in cell wall
- Cell wall is mpermeable to stains and antibiotics
- High G+C content
- Tuberculosis + Leprosy
Archaea; membrane bond, lipid variation, cell wall composition.
- Cell membrane is distinguishable from other domains because the lipids have ether bonds (instead of ester)
- Some membranes are monolayer.
- Cell walls are not made of peptidoglycan
Metabolism of Archaea
- Extremophiles that do not require oxygen based on the extreme environments
- Energy is obtained from chemosynthesis or INORGANIC electron sources
- No glycolysis takes place
Kingdom Fungi; Domain, type of cell, cell wall, energy, oxygen requirements, examples.
- Eukarya
- Unicellular or multicellular
- Cell wall is made of chitin.
Chemosynthesis via organic compounds. - 100% need oxygen except for yeast
- Mold, yeast and mushrooms
- NOT organized into tissues.
Kingdom Protista; Domain, type of cell, energy + Examples + type of organisms
- Eukarya
- Unicellular (some multicellular)
- Mostly NON photosynthetic
- Mostly motile
- 100% nned oxygen
- Amoeba, green algae, brown algae diatoms, euglena, myxomyctes, ciliated protozoans
- eukaryotic organisms that cannot be classified in any other kingdom.
Brown algae diatoms
- have cell wall based on silica which is unique to its kingdom.
Kingdom Plantae; Domain, type of cell, energy, O2 requirements, Cell wall or cell membrane, organization
- Eukarya
- Multicellular eukaryotic organisms
- Photosynthesis
- Cell walls
- 100% need oxygen
ex. Mosses, ferns, conifers… - organized into tissues.
Kingdom Animalia; Domain, Cell wall, O2 requirements, energy, nutrient, organization, examples.
- Multicellular organisms of domain eukarya
- NO cell wall
- 100% need oxygen
- Chemosynthesis
- Obtain nutrients via INJESTIONS
- NO microorganisms
- ex. sponges, worms, insects, rotifers, vertebrates
- Organized into tissues.
Multicellular means…
Organisms that consist of more than one cell.
Can be DIFFERENT cells or IDENTICAL cells.
Colony of identical cells = microorganisms
Colony of differentiated cells = not microorganisms
Mycolic acid
Compounds similar to waxes found in cell wall.
This makes the bacteria highly impermeable to stains
Why are mycobacteria considered to be gram positive?
- They have a cell wall without external membrane.
- They also have a cell wall that traps stains in a similar way
Spores are resistant to…
Heat, dehydration, UV + other chemical treatments.
highly impermeable.
What happens to spores when they are found in unfavorable conditions?
Sporogenesis:
- differentiation of vegetative cell into endospore (spore within a cell)
- Dominant + tough structure that gives protection to spores.
Spore
Cell can differentiate into this different cell type.
- Cell can die and spores can be “stored” until a new host comes along.
- ejected from dead cells
Endospore
- Spore that is within a vegetative cell
- coated with resistant coating (aka cell)
Sporangium
Endospore + cell