Classification
Chapter 17
17-1 Taxonomy
Process of classifying organisms and
giving each a universally accepted name
 Used to study organisms and group them
in logical manner

Scientific names
Usually written in Latin or Greek
 Naming system developed by Carolus
Linnaeus uses two words called binomial
nomenclature
 Each species gets two-part name

The first word is capitalized and names the
Genus to which the organism belongs
 The second word is lower case and unique to
the species naming one particular trait

Hierarchy of classification
Kingdom-largest and very broad
 Phylum
 Class
 Order
 Family
 Genus
 Species-smallest and very specific

Life’s Six Kingdoms
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17-2 Evolutionary classification
Categories of classification represent lines
of evolutionary descent as well as physical
traits
 Process call phylogeny
 Members of a genus share a recent
common ancestor

Cladograms
Identifies characteristics that are new or
recently developed called derived
characters
 Used to construct cladograms that show
evolutionary relationships among similar
organisms
 Help scientists understand how one
lineage branched from another

Similarities in DNA and RNA
Can be used to determine classification
and evolutionary relationships
 DNA can show how organisms change
over time
 The more similar the DNA, the more
recently they shared a common ancestor,
the more closely related the organisms are

Molecular clocks
Uses DNA comparisons to estimate the
length of time two species have been
evolving independently
 Mutations occur all the time causing
changes in DNA

Some cause major effects in phenotype
 Others are neutral and are used in studies to
determine how long ago organisms shared a
common ancestor

17-3 Six-kingdom system
Eubacteria
 Archaebacteria
 Protista
 Fungi
 Plantae
 Animalia

3-domain system
Eukarya-protists, fungi, plants, animals
 Bacteria-Eubacteria
 Archaea-Archaebacteria

Domain Bacteria
Unicellular
 Prokaryotes
 Cells walls contain peptidoglycan
 Ecologically diverse
 Range from free-living to parasites

Domain Archaea
Unicellular
 Prokaryotes
 Live in extreme environments
 Most survive only in the absence of
oxygen
 No peptidoglycan
 Unusual lipids in cell membranes

Domain Eukarya
All organisms with a nucleus
 Some unicellular, some multicellular
 Some photosynthetic
 Some have cell walls
 All eukaryotes

Protista
Most single-celled
 Few multicellular
 Some photosynthetic
 Others heterotrophic

Fungi
Heterotrophs that feed on dead, decaying
organisms
 Secrete enzymes into food and absorb
nutrients
 Most multicellular (except yeast)
 Cell walls of chitin

Plantae
Multicellular
 Photosynthetic
 Autotrophs
 Cell walls of cellulose
 Range from cone-bearing plants to
flowering plants to moss

Animalia
Multicellular
 Heterotrophs
 NO cell walls
 Ability to move during some part of the life
cycle
