Microorganism Classification Quiz

Classification of Microorganisms

• Microorganisms are categorized into five main groups: Bacteria, Archaea, Fungi, Protists, and Viruses.
• Classification is based on characteristics such as cell structure, metabolism, and genetics.

Cell Structure

• Prokaryotes: Lack a nucleus and membrane-bound organelles; DNA is found in the nucleoid. Includes Bacteria and Archaea.
• Eukaryotes: Have a nucleus and membrane-bound organelles. Includes Fungi, Protists, and Animals.

Metabolism

• Autotrophs: Produce their own food using sunlight or chemicals (e.g., plants, algae).
• Heterotrophs: Rely on consuming other organisms or their by-products for nourishment (e.g., animals, fungi, most bacteria).

Genetics

• Domains: Three primary taxonomic classifications: Archaea, Bacteria, and Eukarya.
• Kingdoms: Six kingdoms include Archaea, Bacteria, Fungi, Plantae, Animalia, and Protista.
• Taxonomic hierarchy: Domain > Kingdom > Phylum > Class > Order > Family > Genus > Species.

Bacterial Classification

• Bacteria are classified by:
  • Shape:
    • Cocci (spherical)
    • Bacilli (rod-shaped)
    • Spirilla (spiral)
    • Vibrios (comma-shaped)
  • Cell Wall Composition:
    • Gram-positive: Thick peptidoglycan layer.
    • Gram-negative: Thinner cell wall with an outer membrane.
  • Respiration Mode:
    • Aerobic: Require oxygen.
    • Anaerobic: Do not require oxygen.
  • Nutrition Mode:
    • Autotrophs: Self-sufficient in food production.
    • Heterotrophs: Need to consume other organisms.

Fungal Classification

• Three types of fungi:
  • Filamentous Fungi: Composed of hyphae; can form molds.
  • Yeasts: Unicellular, oval-shaped organisms ranging from 2-60 µm, some capsulated.
  • Dimorphic Fungi: Change form based on temperature; appear filamentous at lower temps and yeasts at higher temps (e.g., Histoplasma capsulatum).

Viral Classification

• Viruses are classified by:

  • Virion Morphology: Size, shape, and presence of an envelope.
  • Genome Properties: Characteristics of viral nucleic acids.
  • Protein Properties: Type of proteins present.
  • Biological Properties: Such as host range.
  • Genome Organization: Structure and replication mechanisms.
  • Antigenic Properties: Immune response characteristics.

• Per the International Committee on Taxonomy of Viruses (ICTV), over 30,000 viruses have been isolated, categorized into more than 3,600 species across 164 genera and 71 families.

Viral Taxonomic Structure

• Taxonomic levels for viruses include:

  • Order (-virales)
  • Family (-viridae)
  • Subfamily (-virinae)
  • Genus (-virus)
  • Species

• Example:

  • Order: Mononegavirales
  • Family: Filoviridae
  • Genus: Filovirus
  • Species: Ebola virus Zaire

Classification by Nucleic Acid

• DNA Viruses:
  • Single-stranded (ssDNA): Parvoviridae.
  • Double-stranded (dsDNA): Papovaviridae, Adenoviridae, Herpesviridae, Iridoviridae, Poxviridae.

Test your knowledge on the classification of microorganisms, focusing on their groups, cell structures, metabolism, and genetics. This quiz covers essential concepts including prokaryotes, eukaryotes, autotrophs, and heterotrophs. Get ready to explore the fascinating world of microbes!