Title: Classification:
1Classification
- 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?
2Why 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.
3Early 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.
4Binomial 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
5Linnaeus'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
6The 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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8Checkpoint 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?
9Modern 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
10Classification 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.
11Traditional 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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12Modern 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.
13Modern 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 -
14Checkpoint 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
15Kingdoms and Domains
- The six-kingdom system of classification includes
the following kingdoms - Eubacteria
- Archaebacteria
- Protista
- Fungi
- Plantae
- Animalia.
16The 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.
17Cladogram 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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18Key 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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19Section 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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20Checkpoint 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?