Classification and Taxonomy

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Classification and Taxonomy
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Why Classify???

• Scientists classify organisms in order to
  organise the great diversity of organisms into
  manageable groups to aid study
• Classification systems have two features
• A universally accepted name for each organism (so
  all scientists all over the world know they are
  talking about the same thing)
• A placement of organisms into groups that have a
  real biological meaning
• Organisms in the same group share important
  traits or characteristics.

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The System of Carolus Linnaeus

• Developed by Carolus Linnaeus, a Swedish botanist
• It is called binomial nomenclature
• Details
• Gives each organism a two part name
• The first part tells the genus of the organism
• The second part tells the species often a Latin
  description of some important characteristic

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Example of Binomial nomenclature

• Acer palmatum

• Acer rubrum

• Acer- maple
• Palmatum latin for hand

• Acer the genus name for all maples
• Rubrum latin word for red

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Notation

• Capitalize the genus name, but not the species
• The name must be written in italics
• Orcinus orca
• Haliaeetus leucocephalus

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The Classification System of Linnaeus

• After naming organisms he grouped them according
  to shared body features.
• Organisms that shared important characteristics
  were classified as the same group.
• Taxa groups
• Taxonomy the science of naming organisms and
  assigning them into species

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Details

• The smallest taxon is species a group of
  organisms that share similar characteristics and
  that can breed with one another
• If two species share many features, but are
  clearly separate biological units, they
  classified as different species within the same
  genus
• eg. Felis domesticus
• Eg. Felis concolor

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Family

• A family is a larger taxon than a genus
• For example the genera Felis and Panthera belong
  to Felidae (cats)
• Felidae Panthera tigris Felidae Felis lynx

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Order

• The next larger taxon is called Order
• For example cats (felidae) and dogs (Canidae)
  belong to Carnivora (meat eater)

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Class, Phyla, Kingdom

• Orders are grouped into Classes (Mammalia)
• Classes are grouped into Phyla (Chordata)
• Phyla are grouped into Kingdom (Animalia)
• Kingdom
• Phylla
• Class
• Order
• Family
• Genus
• Species
• (King Phillip Cuts Open Five Green Snakes)

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Five Kingdom System

• Monera
• Protista
• Fungi

• Plantae
• Animalia

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Five Kingdoms
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Monera

• All monerans are prokaryotes
• Characteristics
• Lack nuclei
• Lack mitochondria
• Lack chloroplasts
• Reproduce by binary fission

• Escherichia coli

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Protista

• All protists are single celled eukaryotic
  organisms
• Characteristics
• Has nucleus
• Have organelles which can include chloroplasts
• Kingdom Protista is divided into three groups
• Animal-like
• Plant-like
• Fungi-like

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• Giardia
• Diatoms
• Slime mold

• Animal like
• (unicellullar, find food from the environment,
  move to find food source)
• Plant like
• (unicellular, make their own food
  (photosynthetic)
• Fungi like
• (find food from the environment, reproduce my
  producing spores, have cell walls)

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Fungi

• Have cell walls but dont contain cellulose
• Do not carry out photosynthesis
• Have many nuclei but not in separate cells

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Plantae

• All plants
• Are Multicellular
• Have cell walls containing cellulose
• Autotrophic Able to carry out photosynthesis
  using chlorophyll

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Animalia

• All animals are
• Multicellular
• Heterotrophic (can not make its own food and
  obtains energy from food it eats)
• Lack cell walls

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Taxonomy Today

• Why things have changed?
• Only the taxon species has a clear biological
  identity
• Members share a common gene pool because they
  interbreed
• The organisms themselves decide who belongs and
  who doesnt to their species
• All other taxa are constructed by biologists
• They try to use biologically important
  characteristics, but different biologists have
  different opinions
• Some species have been moved into different taxa
  (and others will be in the future)

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Taxonomy and Evolutionary Relationships

• Evolutionary theory states that living species
  have evolved from earlier species.
• Thus, taxonomists group organisms in ways that
  show evolutionary relationships.
• By identifying and studying homologous structures
  in
• Adult organisms
• Developing embryos and in
• Well preserved fossils.

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1. Species with homologous structures are classified
   together.
2. Species with analogous structures are put in
   different groups.

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Biochemical Taxonomy

• Taxonomists use molecular similarities to
  classify organisms
• Biochemical similarities
• All organisms (except some viruses) use DNA to
  carry genetic information
• Organisms may be different but their genes and
  the proteins that they make are very similar
• The sequence of the cytochrome c protein (used in
  the electron transport chain) is carried by all
  organisms, but differs slightly between species
• These differences have been caused by mutations
  that occur after the ancestors of the living
  species diverged
• To help us classify organisms into groups,
  taxonomists can compare
• Nucleotide sequences in DNA and RNA
• Amino acid sequences of proteins