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Title: Classification:


1
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?

2
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.

3
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.

4
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

5
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

6
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

7
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8
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?

9
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

10
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.

11
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
Go to Section
12
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.

13
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

14
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  

15
Kingdoms and Domains 
  • The six-kingdom system of classification includes
    the following kingdoms
  • Eubacteria
  • Archaebacteria
  • Protista
  • Fungi
  • Plantae
  • Animalia.

16
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.

17
Cladogram of Six Kingdoms and Three Domains
Section 18-3
DOMAIN ARCHAEA
DOMAIN EUKARYA
Kingdoms
Eubacteria Archaebacteria Protista Plantae Fungi A
nimalia
DOMAIN BACTERIA
Go to Section
18
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
Go to Section
19
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
Go to Section
20
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?
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