Overview of Microorganisms

Introduction

• Presented by Cathy with Level Up RN
• Focus on the three-domain system for classifying organisms
• Discusses differences between prokaryotes and eukaryotes
• Covers key attributes of various microorganisms: bacteria, archaea, protozoa, algae, parasites, fungi, and viruses
• Quiz at the end to test understanding

Three-Domain System

• Classification based on cell's RNA, cell membrane structure, and sensitivity to antibiotics
• Domains of life:
  • Bacteria: Prokaryotes with DNA not enclosed in a nuclear membrane; cell walls contain peptidoglycan
  • Archaea: Prokaryotes without peptidoglycan in cell walls; survive in extreme environments
  • Eukarya: Eukaryotes with DNA enclosed in a nuclear membrane; includes plants, animals, fungi, protozoa, algae, and parasites
• Acellular infectious agents: viruses, viroids, prions

Prokaryotes vs Eukaryotes

• Size:
  • Prokaryotic cells: 0.2 - 2 micrometers
  • Eukaryotic cells: 10 - 100 micrometers
• DNA:
  • Prokaryotes: Single circular chromosome in nucleoid
  • Eukaryotes: Multiple linear chromosomes in nucleus
• Organelles:
  • Prokaryotes: Lack organelles
  • Eukaryotes: Contain organelles such as mitochondria, lysosomes
• Cell Division:
  • Prokaryotes: Divide by binary fission
  • Eukaryotes: Divide by mitosis

Microorganisms

Bacteria

• Unicellular prokaryotes
• Cell walls contain peptidoglycan
• Divide via binary fission
• Most are harmless; some pathogenic
• Photosynthetic bacteria can convert sunlight to energy
• May have flagella for movement

Archaea

• Unicellular prokaryotes
• Cell walls lack peptidoglycan
• Not harmful to humans
• Survive in extreme environments:
  • Methanogens: Anaerobic, produce methane
  • Halophiles: Survive in salty environments
  • Thermophiles: Survive in hot environments

Protozoa

• Unicellular eukaryotes
• Reproduce asexually or sexually
• Can be free-living or parasitic; some pathogenic
• Movement via pseudopods, flagella, or cilia
  • Example: Giardia, a parasitic protozoan causing diarrhea

Algae

• Unicellular or multicellular eukaryotes
• Reproduce sexually or asexually
• Cell walls composed of cellulose
• Live in aquatic environments; most are photosynthetic
• Some can produce toxins (e.g., blue-green algae)

Parasites

• Eukaryotes; unicellular or multicellular
• Depend on other organisms for nutrition
• Types:
  • Helminths: Multicellular endoparasites (e.g., roundworms)
  • Ectoparasites: Live outside hosts (e.g., ticks, fleas)

Fungi

• Eukaryotes; unicellular or multicellular
• Cell walls composed of chitin
• Reproduce sexually or asexually
• Non-photosynthetic
• Types include yeast, mold, and dimorphic fungi
  • Yeast: Unicellular; some beneficial, some pathogenic
  • Mold: Multicellular; can be beneficial or produce toxins
  • Dimorphic Fungi: Mold in cold, yeast in heat

Viruses

• Acellular
• Consist of DNA or RNA in a protein coat
• Obligate intracellular parasites
• Reproduce only within a host cell

Quiz

1. Eukaryote with cell wall of chitin (Answer: Fungi)
2. Unicellular prokaryote with peptidoglycan (Answer: Bacteria)
3. Eukaryote with cellulose wall, photosynthetic (Answer: Algae)
4. Unicellular prokaryote, extreme environments, lacks peptidoglycan (Answer: Archaea)
5. Acellular agent with DNA or RNA, protein coat (Answer: Virus)

Conclusion

• Recap of the key points
• Encouragement to subscribe, like, and share the video