Biology Lecture: Archaea and Extremophiles

Introduction

• Movie Trailer Voice Concept: Used humorously to introduce biology topics.
• Fermentation Example: Yeast, a fungus, performs fermentation in the absence of oxygen.

Archaea: An Exciting Topic

• Unicellular Organisms: Archaea are among the most exciting due to their ability to live in extreme environments.
• Extreme Environments: Include harsh temperatures and high salt levels.
• Extremophiles: Both archaea and bacteria can be extremophiles.

Historical Terminology

• Archaebacteria: An outdated term; archaea are not bacteria.

Similarities and Differences: Archaea vs. Bacteria

• Similarities:
  • Both are unicellular and prokaryotic (no nucleus, no membrane-bound organelles).
  • Share genetic materials, cytoplasm, and ribosomes.
  • Can be autotrophs or heterotrophs.
  • Reproduce via binary fission.
• Differences:
  • Classified into different domains: Bacteria, Archaea, Eukarya.
  • Membrane Structure:
    • Archaea: Ether linkages, sometimes a lipid monolayer.
    • Bacteria: Ester linkages, lipid bilayer.
  • Cell Wall Structure:
    • Archaea: Diverse, no peptidoglycan, may have pseudopeptidoglycan.
    • Bacteria: Peptidoglycan present in gram-positive and gram-negative.
  • Genetics:
    • Archaea DNA: Circular, multiple origins of replication.
    • More genetic similarities between Archaea and Eukarya than with Bacteria.

Challenges in Cultivation

• Culturing Archaea: Difficult due to unknown growth media, nutrients, and environmental requirements.

Example of Archaea: Genus Sulfolobus

• Habitat: Volcanic springs, high temperature (80°C), and acidic conditions.
• Resistance: Can withstand hydrogen sulfide.
• Research Interest: Potential applications in industrial waste treatment and conversion.

Conclusion

• Encouragement: Stay curious about biological sciences.

These notes summarize the key points about archaea and their comparison with bacteria, highlighting their unique adaptations and potential applications.