Classification

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Classification
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Why classify organisms?
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A. Biologists use the characteristics of each
species to classify it with organisms that have
similar characteristics
1. Taxonomy
a. Branch of biology that names and groups
organisms according to characteristics and
biological (evolutionary) history
i. evolution means change over time...thats
all it means!
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History of Classification
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A. Aristotle
1. Over 2000 years ago, classified living things
as plants or animals
a. land dwellers, water dwellers, air dwellers
b. plants into categories based on stems
B. 1400s-1500s
1. Rapid scientific exploration made scientists
realize that Aristotles categories were not
accurate
2. Found that common names lead to confusion
because they vary from place to place
a. Example Black snake in Georgia refers to 6
different snakes
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3. Found that common names may not describe
species accurately
a. Example Jellyfish is really not a fish
4. Early scientific names were long descriptions
in Latin which were hard to remember
a. Also didnt suggest how species were related
C. Linnaeus (1701-1778)
1. Used hierarchical categories based on
morphology (form and structure)
2. Made 7 levels of organization, each more
specific than the last
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a. Kingdom
b. Phylum
c. Class
d. Order
e. Family
f. Genus
g. Species
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Example Bobcat
a. Kingdom Animalia
b. Phylum Chordata
c. Class Mammalia
d. Order Carnivora
e. Family Felidae
f. Genus Lynx
g. Species Lynx rufus or Lynx rufus
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How are organisms classified today?
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A. Rules of Binomial Nomenclature
1. Genus is capitalized and species is lowercase
2. Genus and species are either underlined or
italicized
3. Names are in Latin (so they are the same in
every language)
B. Today, taxonomists use additional levels of
organization
1. Varieties
a. Plants within the same species
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2. Subspecies
a. Animals within the same species that may be
split geographically
3. Phylogeny/evolutionary history
a. Using a family tree, it shows relationships
between groups of organisms
i. example giant panda and other bear
species
4. Morphology (form and structure)
a. Common ancestry
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5. Embryological Patterns of Development
a. Early patterns of embryo development
suggests relationships
6. Chromosomes and Macromolecules
a. Compares DNA, RNA, proteins, etc.
b. Compares amino acid sequences
c. Compares karyotypes looking for regions
with same gene patterns/banding
7. Biogeography
8. Behavior
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From Kingdom to Species
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6 Kingdom System
Animalia Plantae Fungi Protista Eubacteria Archaea
bacteria
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3 Domains

• Bacteria Common Bacteria
• Archaea ancient Bacteria
• Eukarya Protist, Fungi, Plants, and Animals

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4. Three Domain System

• 1. Domain Bacteria
• Corresponds to Eubacteria Kingdom
• Unicellular Prokaryotic Organisms
• No Nucleus
• Ecologically Diverse live everywhere!
• Metabolically Diverse
• Cell Walls contain substance called Peptidoglycan
  (special protein and sugar)
• Target of many Antibiotics

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Three Domain System

• 2. Domain Archaea Ancient Bacteria
• Corresponds to Kingdom Archaeabacteria
• Unicellular, Prokaryotes
• Metabolically Diverse
• No nucleus
• Live in Extreme environments like those of early
  Earth
• Cell walls without Peptidoglycan
• A trait used to distinguish between Archaea and
  Bacteria Domains

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Three Domain System

• 3. Eukarya
• Contains Kingdoms
• Protista, Fungi, Plantae, Animalia
• Eukaryotic, single or multi-cellular Organisms
• Nucleus
• Most visible life
• Humans are in Domain Eukarya