Classification:

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Classification

• Georgia Performance Standards
• Compare how structures and functions vary between
  the six kingdoms (archaebacteria, eubacteria,
  protists, fungi, plants, and animals).
• Examine the evolutionary basis of modern
  classification systems
• Essential Questions
• How does the evidence of evolution contribute to
  modern classification systems?
• Why classify?
• 3. On what criteria do Taxonomists base their
  classification of organisms?
• 4. In what way does scientific discovery lead to
  the development of a new classification group?

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Why Classify?

• To study the diversity of life, biologists use a
  classification system to name organisms and group
  them in a logical manner.
• In taxonomy, scientists classify organisms and
  assign each organism a universally accepted name.
  
• By using a scientific name, biologists can be
  certain that everyone is discussing the same
  organism.

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Early Efforts at Naming Organisms

• The first attempts at standard scientific names
  often described the physical characteristics of a
  species in great detail.
• Results in long names (ex. Rosa sylvestris
  inodora seu canina wild briar rose
• Difficult to standardize the names of organisms
• (other scientists called the wild briar rose
  Rosa sylvestris alba cum rubore, folio glabro )
• Different scientists described different
  characteristics.

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Binomial Nomenclature

•  Carolus Linnaeus developed a two-word naming
  system called binomial nomenclature.
• In binomial nomenclature, each species is
  assigned a two-part scientific name.
• The scientific name is always written in italics
  or underlined.
• The first word (the genus) is capitalized
• The second word (the species) is lowercased.
• EX- Genus species or Genus species
• Humans- Homo sapien

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Linnaeus's System of Classification

• A group or level of organization is called a
  taxonomic category, or taxon

• Linnaeus had 7-
• Kingdom King
• Phylum Phillip
• Class Came
• Order Over
• Family For
• Genus Great
• Species Spaghetti

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The 7 taxonomic categories

• Species - a group of organisms that breed with
  one another and produce fertile offspring.
• Genus - a group of closely related species.
• Family - genera that share many characteristics.
• Order - is a broad taxonomic category composed
  of similar families.
• Class - is composed of similar orders.
• Phylum- several different classes that share
  important characteristics.
• Kingdom - largest taxonomic group, consisting of
  closely related phyla

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Checkpoint Questions

• 1.  How are living things organized for study?
• 2. Describe the system for naming species that
  Linnaeus developed.
• 3. What are the seven taxonomic categories of
  Linnaeuss classification system?
• 4. Why do scientists avoid using common names
  when discussing organisms?
• 5.   Which category has more biological
  meaningall brown birds or all hawklike birds?
  Why?

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Modern Evolutionary Classification 

• Organisms are grouped into categories that
  represent lines of evolutionary descent, not just
  physical similarities
• This strategy of grouping organisms together
  based on their evolutionary history is called
  evolutionary classification.
• Modern classification systems are based upon
  biochemical and genetic evidence that indicates
  evolutionary relationships

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Classification Using Cladograms

• Cladistic analysis identifies and considers only
  the characteristics that arise as lineages evolve
  over time.
• Characteristics that appear in recent parts of a
  lineage but not in its older members are called
  derived characters.
• Derived characters can be used to construct a
  cladogram, a diagram that shows the evolutionary
  relationships among a group of organisms.

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Traditional Classification Versus Cladogram
Section 18-2
Appendages
Conical Shells
Crustaceans
Gastropod
Crab
Crab
Limpet
Limpet
Barnacle
Barnacle
Molted exoskeleton
Segmentation
Tiny free-swimming larva
TRADITIONAL CLASSIFICATION
CLADOGRAM
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Modern Evolutionary Classification 

• Similarities in DNA and RNA
• The genes of many organisms show important
  similarities at the molecular level that can be
  used as criteria to help determine classification.

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Modern Evolutionary Classification

• Molecular Clocks
• Comparisons of DNA can also be used to mark the
  passage of evolutionary time.
• A model known as a molecular clock uses DNA
  comparisons to estimate the length of time that
  two species have been evolving independently.

• Comparison reveals more DNA in common, the more
  recent the common ancestor

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Checkpoint Questions

• How is information about evolutionary
  relationships useful in classification?
• How are genes used to help scientists classify
  organisms?
• 3. What is the principle behind cladistic
  analysis?
• 4. Describe the relationship between
  evolutionary time and the similarity of genes in
  two species.
• 5. How have new discoveries in molecular biology
  affected the way in which we classify organisms
  compared with the system used by Linnaeus?
  Constructing a Chart  

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Kingdoms and Domains 

• The six-kingdom system of classification includes
  the following kingdoms
• Eubacteria
• Archaebacteria
• Protista
• Fungi
• Plantae
• Animalia.

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The Three-Domain System

• The domain is the most inclusive taxonomic
  category larger than a kingdom   
• The three domains are
• Bacteria kingdom Eubacteria
• Archaea, kingdom Archaebacteria
• Eukarya Kingdom protists, fungi, plants, and
  animals.

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Cladogram of Six Kingdoms and Three Domains
Section 18-3
DOMAIN ARCHAEA
DOMAIN EUKARYA
Kingdoms
Eubacteria Archaebacteria Protista Plantae Fungi A
nimalia
DOMAIN BACTERIA
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Key Characteristics of Kingdoms and Domains
Classification of Living Things
Eukarya
Bacteria Eubacteria Prokaryote Cell walls
with peptidoglycan Unicellular Autotroph
or heterotroph Streptococcus, Escherichia coli
Archaea Archaebacteria Prokaryote Cell walls
without peptidoglycan Unicellular Autotroph
or heterotroph Methanogens, halophiles
Protista Eukaryote Cell walls of cellulose in
some some have chloroplasts Most unicellular
some colonial some multicellular Autotroph or
heterotroph Amoeba, Paramecium, slime molds,
giant kelp
DOMAIN KINGDOM CELL TYPE CELL
STRUCTURES NUMBER OF CELLS MODE OF
NUTRITION EXAMPLES
Plantae Eukaryote Cell walls of cellulose
chloroplasts Multicellular Autotroph Mos
ses, ferns, flowering plants
Fungi Eukaryote Cell walls of chitin Most
multicellular some unicellular Heterotroph Mu
shrooms, yeasts
Animalia Eukaryote No cell walls or
chloroplasts Multicellular Heterotroph Sp
onges, worms, insects, fishes, mammals
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Section 18-3
Living Things
are characterized by
Important characteristics
which place them in
and differing
Domain Eukarya
Cell wall structures
such as
which is subdivided into
which place them in
which coincides with
which coincides with
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Checkpoint Questions

• What are the six kingdoms of life as they are now
  identified?
•  What are the three domains of life?
• 3. Why was the kingdom Monera divided into two
  separate kingdoms?
• 4. Why might kingdom Protista be thought of as
  the odds and ends kingdom?
• 5. Which kingdoms include only prokaryotes? Which
  kingdoms include only heterotrophs?