1. Georgia Performance Standards:
Classification:
Georgia Performance Standards:
Compare how structures and functions vary between the six kingdoms (archaebacteria, eubacteria, protests, 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
Difficult to standardize the names of organisms
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.
The first word (the genus) is capitalized
The second word (the species) is lowercased.

5. Linnaeus's System of Classification
A group or level of organization is called a taxonomic category, or taxon
The are 7 taxonomic categories. (from smallest to largest)
species
genus
family
order
class
Phylum
kingdom.

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

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 Linnaeus’s classification system?
4. Why do scientists avoid using common names when discussing organisms?
5.   Which category has more biological meaning—all 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 TRADITIONAL CLASSIFICATION
Section 18-2
Appendages
Conical Shells
Crustaceans
Gastropod
Crab
Barnacle
Limpet
Crab
Barnacle
Limpet
Molted exoskeleton
Segmentation
Tiny free-swimming larva
TRADITIONAL CLASSIFICATION
CLADOGRAM
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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
Animalia
DOMAIN BACTERIA
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18. Classification of Living Things
Key Characteristics of Kingdoms and Domains
Classification of Living Things
Eukarya
DOMAIN
KINGDOM
CELL TYPE
CELL STRUCTURES
NUMBER OF CELLS
MODE OF NUTRITION
EXAMPLES
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
Plantae
Eukaryote
Cell walls of cellulose; chloroplasts
Multicellular
Autotroph
Mosses, ferns, flowering plants
Fungi
Eukaryote
Cell walls of chitin
Most multicellular; some unicellular
Heterotroph
Mushrooms, yeasts
Animalia
Eukaryote
No cell walls or chloroplasts
Multicellular
Heterotroph
Sponges, worms, insects, fishes, mammals
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19. Section 18-3 Living Things
Eukaryotic cells
Prokaryotic cells
are characterized by
Important characteristics
and differing
which place them in
Domain Eukarya
Cell wall structures
such as
which is subdivided into
which place them in
Kingdom Plantae
Kingdom Protista
Kingdom Fungi
Kingdom Animalia
Domain Bacteria
Domain Archaea
which coincides with
which coincides with
Kingdom Eubacteria
Kingdom Archaebacteria
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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?