Introduction to Microbiology

Overview

• Microbiology: Study of microscopic organisms, including:
  • Bacteria
  • Viruses
  • Fungi
  • Protozoa
• Importance:
  • Beneficial microorganisms aid in digestion in humans, nitrogen fixation in plants, and cellulose digestion in animals.
  • Used in industrial applications.

Classification of Microorganisms

• Bacteria:
  • Classified using Gram stain: positive or negative.
• Viruses:
  • Classified by genome type: DNA/RNA, single/double-stranded.
• Fungi:
  • Divided into molds (multicellular) and yeasts (unicellular).

Hierarchy of Classification

• Domain > Kingdom > Phylum > Class > Order > Family > Genus > Species
  • Mnemonic: "Dina's kids prefer candy over fried green spinach."
• Domains:
  • Bacteria, Archaea (Prokaryotes)
  • Eukarya (Eukaryotes)
• Differences between prokaryotes and eukaryotes:
  • Prokaryotes lack cytoplasmic structures like mitochondria, Golgi apparatus, and ER.
  • Eukaryotes lack cell walls (except in fungi and plants) and have different ribosomal structures.

Bacterial Classification and Naming

• Naming: Two parts - Genus and Species (e.g., Staphylococcus aureus)
• Shape-related naming:
  • Cocci: Round cells (e.g., diplococci, streptococci)
  • Bacilli: Rods
  • Spirochetes: Curved
  • Vibrios: Curved rods
  • Tetrads: Packets of four cocci

Bacterial Architecture

• Basic components:
  • Genetic material, cell membrane, cytoplasm
  • Additional structures:
    • Cell wall
    • Flagella (locomotion)
    • Pili (attachment)
    • Plasmid (extra chromosome)
    • Glycocalyx (protection) - can be capsule or biofilm
    • Porins (antibiotic resistance)
    • Mesosomes (respiration)

Gram Staining

• Gram-positive Bacteria:
  • Thick peptidoglycan layer
  • Stain blue
  • Contains teichoic and lipoteichoic acids
• Gram-negative Bacteria:
  • Thin peptidoglycan layer
  • Outer membrane with phospholipids, trans-proteins, and lipoproteins
  • Stain red/pink
  • Lipopolysaccharide layer (endotoxins) causing immune response

Conclusion

• Microbiology is foundational in understanding microorganisms and their impact.
• Feedback and engagement encouraged for further learning.