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Chapter 1 — Chapter 1 — Biodiversity and Classification
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📘Easy summary
Carl Woese (1990), using rRNA sequences, proposed three domains. Bacteria: prokaryotes, cell walls with peptidoglycan, ester-linked membrane lipids, 70S ribosomes, no introns. Archaea: prokaryotes, no peptidoglycan (pseudomurein/protein walls), ether-linked branched lipids, histone-like proteins, RNA polymerase similar to eukaryotes; often extremophiles (thermophiles, halophiles, methanogens). Eukarya: membrane-bound nucleus and organelles, 80S ribosomes, unicellular or multicellular. Taxonomic hierarchy: Domain → Kingdom → Phylum (Division in plants) → Class → Order → Family → Genus → Species.
⭐Key points
- Archaea: ether lipids, no peptidoglycan.
🔬Diagram
🌿Real-life example
Methanogens in cattle gut are Archaea.
💡Exam tip
- Learn hierarchy order.
✅Quick check
1. Extreme environments, ether lipids:
2. Bacteria vs Archaea:
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