Classification, Taxonomy & Germ Theory

Unit 11: Classification, Taxonomy & Germ Theory Fundamental Concepts and Skills
1. Taxonomy

  • What it is: Taxonomy is the way scientists group and name living things based on their shared features.

    • What they look at:

      • Their body parts (anatomy)

      • Their chemical makeup (like DNA)

      • How they evolved over time (from fossils)

2. Historical Perspective

  • Carolus Linnaeus (1700s):

    • Created a simple way to classify organisms that we still use today.

    • Developed a ranking system for organizing creatures, from biggest group to smallest:

      • Kingdom (biggest)

      • Phylum

      • Class

      • Order

      • Family

      • Genus

      • Species (smallest, most specific)

    • Easy way to remember: "King Phillip Came Over For Great Spaghetti" or "Kids Prefer Candy Over Fresh Green Salad."

    • Introduced Binomial Nomenclature:

      • Every organism gets a special two-word scientific name.

      • How names work: The first word is the genus (general group), and the second word is the species (specific type).

      • Scientific names are usually written in italics or underlined. Examples:

        • Homo sapiens (humans)

        • Canis familiaris (dogs)

        • Escherichia coli (a type of bacteria)

3. Three Domain System

  • Created by: Carl Woese and others in 1990.

  • Domains (the biggest groups of all life):

    • Archaea

    • Bacteria

    • Eukarya

  • How things are classified:

    • Simple cells without a nucleus (prokaryotes) go into either the Archaea or Bacteria domains.

    • All other living things, including animals, plants, fungi, and protists, are in the Eukarya domain.

4. Hierarchical Classification

  • Organisms are sorted into bigger and smaller groups based on how closely they are related, which often shows their evolutionary history.

    • Ways to group them:

    • Similar body structures

    • Evidence from fossils of shared ancestors

    • Similarities in how they develop from an embryo

    • Similar DNA

5. Six Kingdom Classification

  • The Six Kingdoms:

    • Archaea

    • Eubacteria

    • Protista

    • Fungi

    • Plantae (Plants)

    • Animalia (Animals)

  • Dichotomous Key: A tool with yes/no questions that helps you identify an organism step-by-step.

6. Definitions of Species

  • A species is a group of organisms that can breed with each other and have babies that can also have babies (fertile offspring).

  • Important: This is different from inbreeding, which is breeding among close relatives.

7. Viruses

  • What they are like:

    • Viruses are NOT truly alive like cells are.

    • Basic parts: They have genetic material (nucleic acid, like DNA or RNA) wrapped in a protein coat.

    • Viruses are tiny, non-living particles that:

      • Are not cells.

      • Don't meet all the requirements for being called