1. Ch 18- Classification
Why do biologists organize living organisms into groups that have biological meaning?
Study the diversity of life
Use classification system to name organisms and group them in logical manner
Taxonomy- discipline of classifying organisms and assigning each organism a universally accepted name

2. Scientific Names Why don’t scientists use common names?
Use Latin and Greek
Bionomial nomenclature- two word naming system
Each species given two-part scientific name
Carolus Linnaeus
First word is capitalized, second word is lowercased, written in italics
Ursus arctos- grizzly bear
Ursus- genus to which organism belongs
Genus- group of closely related species
artos- unique to each species within the genus

3. Linnaeus’s System of Classification
Linnaeus’s hierarchical system of classification uses seven taxonomic categories
Species
Genus
Family
Order
Class
Phylum
Kingdom
Taxon- taxonomic category
Family- genera that share many characteristics
Ursidae
Order- broad taxonomic category composed of similar families
Carnivora
Class- composed of similar orders
Mammalia
Phylum- several classes that share important characteristics
Chordata
Kingdom- largest and most inclusive categories
Animalia

4. Sec 2- Modern Evolutionary Classification
Phylogeny- evolutionary relationships among organisms
How are evolutionary relationships important in classification?
Organisms are grouped into categories that represent lines of evolutionary descent, or phylogeny- not just physical similarities
Evolutionary classification- grouping organisms together based on their evolutionary history

5. Classification Using Cladograms
Cladistic analysis identifies new characteristics that arise as lineages evolve over time
Derived characters- characteristics that appear in recent parts of a lineage but not in its older members
Evolutionary innovation, or new characteristics
Cladogram- diagram that shows evolutionary relationships among group of organisms
Help understand how one lineage branched from another
Use derived characters

6. Similarities in DNA and RNA
All organisms use DNA and RNA to pass on information
How can DNA and RNA help scientists determine evolutionary relationships?
Genes of many organisms show important similarities at molecular level
Can be used to determine classification and evolutionary relationships
Similar genes
Human muscles and yeast
DNA evidence
More similar DNA sequence of two species, the more recently they shared a common ancestor
American vulture, African vulture, stork

7. Molecular Clocks
Uses DNA comparisons to estimate the length of time that two species have been evolving independently
Relies on mutations
Comparison between DNA sequences can reveal how dissimilar the genes are- indicates how long ago two species shared a common ancestor

8. Sec 3- Kingdoms and Domains
How many kingdoms of life are there?
What are the 6 kingdoms?
Eubacteria
Archaebacteria
Protista
Fungi
Plantae
Animalia
Domain- taxonomic category larger than kingdom
Eukarya- composed of protists, fungi, plants, animals
Bacteria- Eubacteria
Archaea- Archaebacteria

9. Domain Bacteria and Archaea
Bacteria- unicellular and prokaryotic
Thick, rigid cell walls
Ecologically diverse- free living to deadly parasites
Some photosynthetic, some not
Some depend on oxygen, some not
Archaea- unicellular and prokaryotic
Most extreme environments
Many survive only in absence of oxygen
Cell walls lack peptidoglycan
Unusual lipids in cell membranes, not found in any other organism

10. Domain Eukarya All have nucleus Protista, Fungi, Plantae, Animalia
Protista- display greatest variety
Unicellular and multicellular
Photosynthetic and heterotrophic
Fungi- heterotrophs
Feed on dead or decaying organic matter
Unicellular or multicellular
Plantae- multicellular organisms that are photosynthetic autotrophs
Animalia- multicellular and heterotrophic
Incredible diversity