Lecture on Classification of Organisms

Introduction

• Focus on classification of organisms based on characteristics.
• Learn about the three-domain classification system.
• Understand how evolutionary trees depict relationships between organisms.

Historical Background

• Carolus Linnaeus (1700s): Developed a system to classify species based on structure and characteristics.
  • Two Kingdoms:
    • Animal Kingdom
    • Plant Kingdom
  • Hierarchy of Categories:
    • Kingdom
    • Phylum
    • Class
    • Order
    • Family
    • Genus
    • Species
  • Mnemonic for hierarchy: "King Phillip Came Over For Good Soup"
  • Binomial Nomenclature:
    • Organisms are named using genus and species.
    • Example: Zebra is Equus quagga; Polar bear is Ursus maritimus.

Advances in Biological Classification

• Modern classification utilizes:
  • Microscopy to examine internal structures.
  • Biochemical analysis, including DNA comparisons.

Three-Domain Classification System

• Developed by Carl Woese based on biochemical analysis.
• Domains:
  • Archaea: Primitive bacteria often in extreme conditions (e.g., hot springs).
  • Bacteria: True bacteria, found in places like the human digestive system.
  • Eukaryota: Includes animals, plants, fungi, and protists like amoeba.

Evolutionary Trees

• Used to show how closely related organisms are to each other.
• For living organisms, classification data such as DNA is used.
• For extinct organisms, fossils are used despite incomplete records.
• Example given showing relationships:
  • Species 1 and 2 are closely related.
  • Species 3 is more distantly related but shares a common ancestor with species 1 and 2.

Conclusion

• Emphasized the importance of understanding classification and evolutionary relationships.
• Reference to a revision workbook available for more practice and questions.

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