chapter 2 microorganism

Characteristics of Microorganisms

Course Overview

• Microbiology and Infection Control
• Important Objectives:
  • Define microbiology and its relevance to infection control.
  • Understand various types of microorganisms including bacteria, viruses, fungi, algae, and protozoa.
  • Describe bacterial structures and functions of both prokaryotic and eukaryotic cells.
  • Compare viruses and bacteria.

Major Groups of Microorganisms

1. Bacteria
   • Unicellular, diverse in size, shape, arrangements; optimal growth at 98.6°F.
2. Viruses
   • Much smaller; depend on host cells for replication, can be deadly.
3. Algae
   • Vary from unicellular to multicellular, generally non-pathogenic to humans.
4. Protozoa
   • Large unicellular organisms found in various habitats; some cause infections.
5. Fungi
   • Includes mushrooms, yeast, and molds; oral candidiasis is notable in dental hygiene.
6. Archaea
   • Similar to bacteria but genetically closer to eukaryotes.

Viruses and Prions

• Bacteriophages: Viruses that infect bacteria, discovered in 1915 and 1922.
• Prions: Infectious proteins that cause neurological diseases; not classified as microorganisms. E.g., Creutzfeldt-Jakob disease and mad cow disease.

Cell Types

• Prokaryotic Cells
  • No nucleus or internal membranes.
  • Examples: Bacteria.
• Eukaryotic Cells
  • Have a nucleus and organelles; more complex.
  • Examples: Fungi, plants, animals.

Structures of Prokaryotic Cells

• Flagella: Provides mobility.
• Capsule: Gelatinous covering for protection.
• Cell Wall: Rigid structure that maintains shape.
• Ribosomes: Sites of protein synthesis.
• Nucleoid: Region containing DNA.
• Endospores: Resistant structures for survival.

Structures of Eukaryotic Cells

• Nucleus: Contains genetic material.
• Mitochondria: Powerhouse, produces ATP.
• Endoplasmic Reticulum: Synthesizes lipids and proteins.
• Golgi Complex: Packages proteins.
• Lysosomes: Contain digestive enzymes.