6-4 notes classifying organisms chapter 6, lesson 4
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6-4 Notes Classifying Organisms
Chapter 6, Lesson 4
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Historic Classification Systems• Aristotle, a Greek
philosopher, was one of the first people to put organisms into categories.
• He categorized things as animals, plants, or minerals, and then according to where they lived—air, land, or sea.
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Historic Classification Systems
• In the mid-1700s, Swedish botanist, Linnaeus developed a classification system that grouped organisms by similar physical structures
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Historic Classification Systems• Linnaeus’s
system went from kingdom (most general) to species (most specific).
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Historic Classification Systems
Species
Genus
Family
Order
Class
Phylum
Kingdom
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Historic Classification Systems
• Members of a species group have the greatest number of traits in common and can breed and produce fertile offspring.
• Only species are subject to natural selection and evolve.
Felis catus
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Historic Classification Systems
• Linnaeus also developed a system for naming species that is still used.
• Each species has a two-word scientific name called its species name.
• The first word identifies its genus.
• Human’s species name is Homo sapien.
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Historic Classification Systems
• All small cats have Felis as the first word of their species name, because that is their genus.
domestic cat
Felis catus
sand cat
Felis margarita
jungle cat
Felis chaus
wild cat
Felis silvestris
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Historic Classification Systems• Basic features such as cell type, presence
of a cell wall, or single-celled versus multicellular define each of the 6 kingdoms:
1. Eubacteria2. Archaebacteria3. Protists4. Fungi5. Plantae6. Animalia
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Modern Methods of Classification
• The modern study of classification, called systematics, uses DNA and molecular biology to identify related organisms.
• The more shared DNA sequences two species have, the more recent ancestor they probably share.
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Modern Methods of Classification
• Scientists use haplotypes, samples of 1000 base pairs, to compare DNA sequences among organisms.
• DNA hybridization measures the percentages of DNA that are the same between two organisms.
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Modern Methods of Classification
• Molecular biology led to a new highest level of classification called “Domain,” which is based on differences in a particular genetic sequence. There are 3 domains:
1. Bacteria
2. Archaea
3. Eukarya
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Modern Methods of Classification
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Modern Methods of Classification
• As more sophisticated techniques are developed, the classification system will continue to become more refined.
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Modern Methods of ClassificationThe current system of classification (from highest to lowest):
1.Domain
2.Kingdom
3.Phylum
4.Class
5.Order
6.Family
7.Genus
8.Species
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Cladograms
• Scientists create diagrams called cladograms to group organisms based on certain characteristics.
• A cladogram shows common ancestry, and helps scientists to better understand evolution.
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Cladograms
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Cladograms
MYA
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Cladograms
The National Museum of Natural History - Washington, D.C
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What was Linnaeus’ classification system based on?
A whether things were plant, animal, or mineral
B where organisms lived—air, water, or land
C similar DNA sequences
D similar physical structures
6.4 Classifying Organisms
What approach measures the percentage of DNA that is similar between two organisms?
A DNA hybridization
B DNA sequencing
C haplotypes
D systematics
6.4 Classifying Organisms
What is currently the highest level of classification?
A animalia
B domain
C kingdom
D order
Which of the following does not provide independent evidence for the theory of evolution through natural selection?
A fossil record
B comparative anatomy
C systematics
D molecular biology
Which of the following is not a kingdom?
A protista
B fungi
C eukarya
D animalia
SCI 3.