1. Classifying life Taxonomy
Is the branch of biology that names and classifies species according to a system of broader and broader groups
Species Genus Family Order Class Phylum Kingdom Domain
Mammalia
Ursus ameri-
canus
(American
black bear)
Ursus
Ursidae
Carnivora
Chordata
Animalia
Eukarya
Figure 1.14

2. Classification of Living Things
Over a million species named (so far)
More identified every week!
Est Million left to find?
Why bother with a naming “system”? Need to organize information, make sense of it, look for similarities and differences
Groups organisms based on: Anatomy, Genetics, andEvolutionary history (“relatedness”)

3. History of Taxonomy
Aristotle (384–322 BC) the Greek philosopher was the first to attempt to classify all living things, and some of his groups are still used today, like the vertebrates and invertebrates, which he called “animals with blood and without blood”.
Carolus Linnaeus (Karl von Linne) , was a Swedish botanist, physician, and zoologist, who formalized the modern system of naming organisms called binomial nomenclature, in Systema Naturae (1758)
He is known by the epithet “Father of Modern Taxonomy".

4. Taxa (categories of classification)
3 Domains
6 Kingdoms
Phylum (“Division” for plants)
Class
Order
Family
Genus
Species

6. The Three Domains of Life
Distinguished based on biochemical evidence (differences in rRNA, genes)
Domains Archaea and Bacteria are unicellular organisms lacking membrane-bound organelles like nuclei (Prokaryotes)
Domain Eukarya is organisms whose cells have nuclei (Plants, Animals, Fungi and Protists)

7. Domain Archae Prokaryotes Kingdom Archaebacteria
Single celled, DNA/RNA but no nucleus, few, simple organelles, cell walls)
Kingdom Archaebacteria
Found in extreme environments (similar to those of early earth)
Complex metabolic ability (many are chemosynthetic)
First organisms similar to Archaea?

8. Domain Bacteria Kingdom Eubacteria Unicellular
Prokaryotic cells (no nucleus, few, simple organelles, cell walls)
Found almost everywhere
More of them than any other living thing
Some are autotrophs, some heterotrophs (depends on the species)
Some are pathogens (cause diseases)
Most are harmless and many are vital to human well being
Decompose our wastes
Make vitamins in our guts
Producing certain products that we use (yogurt, cheese)

9. Domain Eukarya Kingdom Protista
Most are one-celled organisms (ex: amoeba, paramecium, euglena)
A few are multicellular (ex: kelp, seaweed)
May be producers or consumers (or both); depends on the species
Some are very “plant-like”, others are very “animal-like”

10. Domain Eukarya Kingdom Fungi Eukaryotic cells
Have cell walls for support (chitin)
Most are multicellular, with a few unicellular species (yeasts)
Heterotrophic; enzymatically digest and absorb nutrients
Mostly decomposers (important for ecosystem nutrient cycling); a few are parasitic

11. Domain Eukarya Kingdom Plantae All are multicellular
Composed of eukaryotic cells with a cell wall made of cellulose
Photosynthetic autotrophs, chlorophyll
Important producers of glucose “fuel” for entire ecosystem

12. Kingdom Animalia Domain Eukarya
All are multicellular (sponges to humans)
Composed of complex, eukaryotic cells, no cell walls (flexible, for mobility)
All are heterotrophic consumers

13. Classification of Living Things
Within Kingdoms, organisms are sorted into Phylum, Class etc.
At species level organisms so closely related they can interbreed
Scientific name = Genus and species names (binomial nomenclature ex. Felis catus, Drosophila melanogaster, Homo sapiens
Genus includes other similar species ex. F. leo and F. tigris or Quercus rubra, Quercus alba
Genus ALWAYS starts with cap, species lower case
Genus and species names are always either underlined or italicized

14. Scientific nomenclature shows both anatomical similarity and evolutionary history