Lecture Notes: Carl Woese and the Classification of Archaea
Introduction
Carl Woese significantly impacted biological classification.
He introduced the concept of a third domain: Archaea.
Previously, organisms were classified as either Bacteria or Eukaryotes.
Differences Between Bacteria and Archaea
General Characteristics
Both are single-celled organisms.
Neither have a nucleus nor membrane-bound organelles.
Both reproduce asexually.
Key Differences
Cell Walls
Bacteria: Contain peptidylglycine.
Archaea: Lack peptidylglycine in their cell walls.
Cell Membranes
Bacteria: Use fatty acid chains.
Archaea: Utilize isoprene chains.
Genetic Code Reading Enzymes
Archaea have unique enzymes differing from bacterial ones.
Habitat and Impact
Archaea often inhabit extreme environments (e.g., hydrothermal vents, hot springs).
Can also be found alongside bacteria in environments like the human gut.
To date, no known archaea cause diseases in humans, unlike certain bacteria.
Modern Classification
Due to these differences, a third domain "Archaea" was proposed and accepted.
Current classification now includes three domains: Bacteria, Archaea, and Eukarya.
Conclusion
The work of Carl Woese fundamentally changed our understanding of life's classification.
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Note: These notes summarize the important points from the lecture on Carl Woese's contribution to biological classification and the distinctions between bacteria and archaea.