Classification (LE2) Flashcards
The science of biological classification
Taxonomy
Grouping organisms into taxa based on mutual similarity or evolutionary relatedness
Classification
Characterization of an isolate to determine what species it is
Identification
Assignment of names to taxonomic groups in agreement with published rules
Nomenclature
Study of diversity of life (both past and present) and the relationships among living things through time
Uses taxonomy as means to understand organisms
Systematics
Collection of strains that share many stable properties in common and differ significantly from other groups of strains
Species (in prokaryotes)
A group of closely related organisms that breed among themselves
Species (in eukaryotes)
Population of organisms that descends from a pure culture isolate or from a species
Strain
Types of classification
Artificial
Natural or Phylogenetic
Based upon the expressed characteristics or the phenotype of the organism
Artificial Classification
Based upon the suggested evolution of the organism (those that share a common ancestor)
Natural or Phylogenetic Classification
Three domains
Bacteria
Archaea
Eukarya
Founded the 3 domains
Carl Woese in 1990
Principles of Nomenclature
Each distinct kind of organism is designated as a species
Latin binomial nomenclature
Names are descriptive
List of species of prokaryotes
Bergey’s Manual of Systematic Bacteriology
Can change if the organism is assigned to another genus because of new information
Generic Name
Stable
The oldest epithet for a particular organism takes precedence and must be used
Specific Name
Rule for naming bacteria
International Code for the Nomenclature of Bacteria (1991)
Questions on Nomenclature
International Journal of Systematic Bacteriology (IJSB)
Involves the study, not of a single cell, but of a population of identical cells
Characterization and Identification
Prerequisite for characterization
Pure Culture
Reasons for characterization
Identification
Comparison with other organisms
Exploit characteristics which may be beneficial
Major characteristics used in taxonomy
Cultural Morphological Metabolic Chemical Composition Antigenic Genetic
Refer to the nutrients required for growth and the physical conditions of an environment that will favor growth
Cultural
Nutritional types
Based on:
Energy source
Carbon source
C and E source
Nutritional types based on energy source:
Phototrophs
Chemotrophs
Based on carbon source:
Autotroph
Heterotroph (organotroph)
Based on E and C source:
Photoautotroph
Photoheterotroph
Chemoautotroph
Chemoheterotroph
Photoautotroph (E and C source)
Sunlight (E)
CO2 (C)
Photoheterotroph
Sunlight (E) Organic compounds (C)
Chemoautotroph
Inorganic chemical (E) CO2 (C)
Chemoheterotroph
Organic compounds (E) Oragnic compounds (C)
Based on physical conditions:
Temperature req.
pH req.
Oxygen req.
Temperature requirement
Psychrophile Mesophile Thermophile Psychrotroph Hyperthermophile
Between -5 and 15C
Psychrophile
Between 25 and 45C
Mesophile
Between 45 and 70C
Thermophile
Between 20 and 30C (but grows well at lower temperatures)
Psychrotroph
Between 70 and 110C
Hyperthermophile
pH Requirement
Acidophile
Neutrophile
Alkalophile
Opt pH below 5.5
Acidophile
Opt pH 5-8
Neutrophile
Opt pH above 8.5
Alkalophile
Oxygen Requirement
Aerobe
Anaerobe
Types of aerobe
Obligate aerobe
Microaerophile
Types of anaerobe
Obligate anaerobe
Facultative anaerobe
Aerotolerant anaerobe
Other examples of cultural characteristics:
Type of growth on agar media
Type of growth on liquid media
Salt tolerance/requirement
Morphological chracteristics
Size
Shape
Arrangement
Structures
Biochemical/physiological characteristics
i.e. presence of enzymes, fermentation of sugar
Metabolic characteristics
Chemical composition
Gram negative
Gram positive
Molecule capable of inducing an immune response on the part of the host organism
Antigen
DNA composition analysis, detection of the likeness or homology between DNA of cell
Genetic composition
