1 Chapter 18- Classification. 2 I. Finding order in Diversity A. Why classify? 1. To study the...

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Chapter 18- Classification

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I. Finding order in Diversity

A. Why classify? 

1. To study the diversity of life, biologists use a classification system to name organisms and group them in a logical manner.

 2. Using taxonomy, scientists classify organisms and assign each organism a universally accepted name.

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B. Assigning Scientific Names

1. By the eighteen-century scientists were finding out that calling organisms by their common name was confusing.

2. Carolus Linnaeus developed a two-name naming system called binomial nomenclature.

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3. Each species is assigned a two –part scientific name.

4. Ex- Homo sapiens

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  C. Linnaeu’s System of Classification 

1. Linnaeus’s hierarchical system of classification includes seven levels.

 2. From the largest to the smallest- kingdom, phylum, class, order, family, genius and specie.

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King Philip Came Over For Good Spagetti

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II. Modern Evolutionary Classificiation

A. Which similarities are most important? 

B. Evolutionary classification 

1. Biologists now group organisms into categories that represent lines of evolutionary descent or phylogeny not just physical similarities. This is called evolutionary classification.

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C. Classification Using Cladograms 

1. Characteristics that appear in recent parts of a lineage but not in its older members are called derived characters.

2. Derived characters can be used to construct a cladogram- a diagram that shows evolutionary relationships among a group of organisms.

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D. Similarities in DNA and RNA

1. The genes of many organisms show important similarities at the molecular level.

2. Similarities in DNA can be used to help determine classification and evolutionary relationships.

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DNA-left RNA-Right

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III. Kingdoms and Domains

A. The tree of Life Evolves

1. The six-kingdom system of classification includes the kingdoms, Eubacteria, Archaebacteria, Protista, Fungi, Plantae and Animalia.

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B. The three- Domain System

1. The domain is a more inclusive category than any other.

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2. The three domains are: 

a. Eukarya-which is composed of protista, fungi, plantae and animals.

 b. The domain bacteria, which

corresponds to the kingdom Eubacteria.  

c. Domain Archaea, which corresponds to archaebacteria.

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C. Domain Bacteria1. Bacteria are unicellular and prokaryotic (does not have a nucleus).

 2. The cell walls contain a substance known as peptidoglycan.

 3. These bacteria are ecologically diverse, ranging from free-living soil organisms to deadly parasites.

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4. Some photosynthesize and some do not.

5. Some need oxygen and some do not.

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C. Domain Archaea

1. They are also unicellular and prokaryotic.

2. Bacteria that live in the most extreme environments possible.

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E. Domain Eukarya 

1. Consists of all organisms that are Eukaryotic (cells that have a nucleus)

 2. Protista are eukaryotes that cannot be classified as a plant, fungus or an animal.

 3. Members of the kingdom Fungi are heterotrophic. Most feed on dead or decaying organic matter

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4. Members of kingdom plantae are multicellular organisms that are photosynthetic and Autotrophic.

5. Members of the kingdom Animalia are multicellular and heterotrophic.

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Protists

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Fungi

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Plants

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Animals

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The End