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CLASSIFICATION
What is does the word classify mean?
Classify -to group things according to
similar/different features
(structures) that they share
Biologist use a classification system to
name and group organisms in a logical
manner.
Taxonomy : It is the science of
classifying organisms and assigning them
universally accepted names.
Binomial Nomenclature
• Binomial nomenclature is a two-words naming
system developed by Carolus Linnaeus.
• In this system, a species is assigned a two-part
scientific name.
– Always written in ITALICS
– First word Capitalized
– Second word lower case
– First word is the genus
– Second word is the species
– Always in Latin
– Example: Homo sapien
7 Levels of Classification
Kingdom broadest level
Phylum
Class
Order
Family
Genus
Species most specific
Each level is called a
taxon
An easy way to remember 
King
Phillip
Came
Over
For
Good
Soup!
Example
1. Grizzly Bear
• Ursus arctos
• Genus = Ursus
• Species = arctos
2. Polar Bear
• Ursus maritimus
• Genus: Ursus
• Species: maritimus
Phylogeny
• Study of evolutionary relationships among
organisms
Cladogram
A diagram that shows the evolutionary relationships
among a group of organisms
Evolutionary Classification
Strategy of grouping organisms together based on their evolutionary
history
Derived characters
Derived characters: These are
characteristics that appear in recent
parts of a lineage but not in its older
members.
Similarities in DNA can be used to
help determine classification and
evolutionary relationships
Molecular Clock
• A model that uses DNA comparisons to
estimate the length of time that two species
have been evolving independently.
Three Domains of life
The six kingdoms are:
6
5
4
3
2
1
Archaebacteria
 “ancient bacteria”
 Unicellular
 Some species are heterotrophs (can’t make
their own food) while some are autotrophs
(can make own food).
They are prokaryotes, meaning they do not
have a nucleus,
 They live in extreme environments (volcano
hot spring)
Survive in the absence of oxygen.
Cell walls lack peptidoglycan.
 Examples: Methanogens, halophiles
Eubacteria
 Like
archaebacteria, they are unicellular and are
prokaryotes.
 Some species are heterotrophs, while others are
autotrophs.
There are both helpful and harmful organisms in this
kingdom.
Have thick, rigid cell wall made up of petidoglycan
Some need oxygen and some don’t
Examples: Gonococcus, streptococcus , E.coli
Checkpoint
1. How are eubacteria and archaebacteria
similar?
2. How are they different?
Protists
 “Odds
and ends”
Mostly unicellular and some
multicellular.
 They are eukaryotes they have a
true nucleus.
Some are autotrophs and some
heterotrophs.
Some have cellulose cell wall &
chloroplast
Examples: Amoeba,
paramecium,
slime mould
giant kelp
Fungi
 Multicellular organisms

Eukaryotes
 Heterotrophs
 Most live dead or
decaying matter.
 Have cell walls made up
of chitin
Example: Mushroom,
yeast
molds
Plants
 Autotrophs
Eukaryotes
Produce oxygen, which many organisms require.
Multicellular
Have cellulose cell wall & Chloroplast
Examples: Mosses,
flowering plants
Ferns
Animals
Multicellular
Eukaryotes
Heterotrophs
 Live in diverse environments
Have no cell wall or chloroplast
Examples: sponges
worms
insects
fishes
mammals
The Three Domains of Life
DOMAIN
Kingdoms
1.
Bacteria :
Eubacteria
2.
Archaea :
Archaebacteria
3. Eukarya :
Protist
Fungi
Plantae
Animalia
2-Examples each.