II. Classification of Microorganisms

II. Classification of Microorganisms A. B. C. D. Principles of Classification and Nomenclature Eukaryotic Organisms Prokaryotic Organisms Viruses

II. A. Principles of Classification and Nomenclature Taxonomy Kingdom Phylum (pl: Phyla) Class Order Family Genus (pl: Genera) Species (pl: Species)

II. A. Principles of Classification and Nomenclature Phylogenetic vs. Phenetic Classification Systems Phylogenetic Classification System: Groups reflect genetic similarity and evolutionary relatedness Phenetic Classification System: Groups do not necessarily reflect genetic similarity or evolutionary relatedness. Instead, groups are

based on convenient or observable characteristics. II. A. Principles of Classification and Nomenclature Definition of species in microbiology Type strains: Known well-characterized pure cultures; references for the identification of unknowns American Type Culture Collection (ATCC)

II. A. Principles of Classification and Nomenclature Species vs. Strain Species: A specific or defined type of organism, defined by similarity with known species. Strain: Genetic variation within a species II. A. Principles of Classification

and Nomenclature Nomenclature Scientific name (Systematic Name) Binomial System of Nomenclature Genus name + species name italicized or underlined genus name is capitalized and may be abbreviated species name is never abbreviated. eg: Bacillus subtilis B. subtilis

II. A. Principles of Classification and Nomenclature Nomenclature (cont.) Common or descriptive names (trivial names) eg: tubercle bacillus (Mycobacterium tuberculosis) meningococcus (Neiserria meningitidis) Group A streptococcus (Streptococcus pyogenes)

II. B. Eukaryotic Organisms Eukaryotic Cells Have: Complex Internal Membrane System Compartmentalization Membrane-Enclosed Organelles DNA is enclosed in a membrane-bound nucleus

Includes: Animal & Plant cells Eukaryotic Microorganisms II. B. Eukaryotic Organisms Eukaryotic Kingdoms Kingdom Protista (Protozoa and Algae) Kingdom Fungi Kingdom Plantae Kingdom Animalia

II. C. Prokaryotic Organisms Prokaryotic Cells Have: No (or few) internal membranes Many processes that are associated with organelles in eukaryotes (eg. respiration, photosynthesis) are mediated by specialized regions of the plasma membrane in prokaryotes II. C. Prokaryotic Organisms

Prokaryotic Cells (cont.) There is no membrane-bound nucleus in prokaryotes. Instead the DNA is located within a specialized region of the cytoplasm of the cell called the nucleoid region. There is no nuclear membrane surrounding the nucleoid. Includes: The Bacteria The terms prokaryotic cell and bacterial cell often are used interchangeably

II. C. Prokaryotic Organisms Prokaryotic Kingdoms Kingdom Eubacteria Kingdom Archaeobacteria II. D. Viruses Structure of a Virus Particle Noncellular Biological Entity Contains either DNA or RNA (not both) Nucleic Acid is surrounded or coated by a protein shell (capsid)

Some viruses possess a membrane-like envelope surrounding the particle II. D. Viruses Viral Replication No independent metabolism or replication Replicate only inside an infected host cell Do not replicate via a process of cell division Replicate via a process of: Attachment and Penetration Disassembly (uncoating)

Synthesis of Viral Protein and Nucleic Acid Reassembly of new viral particles Release of new viral particles