II. Classification of Microorganisms

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

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

3. 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.

4. 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)

5. 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

6. 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 subtilisB. subtilis

7. 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)

8. 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

9. II. B. Eukaryotic Organisms • Eukaryotic Kingdoms • Kingdom Protista(Protozoa and Algae) • Kingdom Fungi • Kingdom Plantae • Kingdom Animalia

10. 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

11. 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 BacteriaThe terms “prokaryotic cell” and “bacterial cell” often are used interchangeably

12. II. C. Prokaryotic Organisms • Prokaryotic Kingdoms • Kingdom Eubacteria • Kingdom Archaeobacteria

13. 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

14. 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