Chapter 17: Classification

Classification The grouping of objects or information based on

similarities Taxonomy: the branch of biology that groups and

names organisms based on their different characteristics

Taxonomists: scientists who study taxonomy Carolus Linnaeus (1707-1778) was a Swedish botanist

that developed binomial nomenclature Binomial nomenclature: two-word naming system

(scientific name) for different species Scientists all over the world can communicate about

an organism using its scientific name, regardless of country, language, etc.

o Written in Latin because Latin is no longer used and therefore does not change

o Each scientific name has two words that are italicized or underlined First word: genus name (capitalized) Second word: species name (not capitalized)

Homo sapiens

Genus Species

Scientists classify organisms based on their characteristics and if they are related through evolution

Taxa Groups into which living things are classified Organisms are organized into 7 taxa

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1. Kingdom 2. Phylum 3. Class 4. Order5. Family 6. Genus 7. Species

Six Kingdoms of Living Things1. Archaebacteria: Bacteria that live in extreme environments (hot springs)2. Eubacteria: Common bacteria3. Protista: Unicellular (Amoeba, Paramecium) and multicellular eukaryotes (kelp) that lack complex organ systems and live in moist environments4. Fungi: Unicellular or multicellular eukaryotes that absorb nutrients from organic materials in the environment (Mushrooms, yeast, molds)5. Animalia: multicellular heterotrophs (animals)6. Plantae: multicellular eukaryotes that carry out

photosynthesis (plants)

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Most broad – has lots of different types of organisms

RememberKing Philip came over for good spaghettiMost specific –

has only 1 type of organism

Gets more

specific

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Most broad – has lots of different types of organisms

Most specific – has only 1 type of organism

Gets more

specific

How do taxonomists determine if organisms are related by evolution? Similar physical characteristics between organisms Similar breeding behavior (mating calls) Same geographical location Same number and structure of chromosomes Similar DNA sequences

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Closely related organisms have more levels of taxonomy in common……………

…..than unrelated organisms

Phylogeny The evolutionary history of a species Cladistics: a biological system of classification based

on phylogenyo As groups of organisms diverge and evolve from a

common ancestor, they keep some of the same traits (derived traits)

o Cladogram: branching diagram that shows the derived traits of a group of organisms (like a pedigree that shows evolution)

o The closer 2 organisms are in a cladogram, the more probable that they are closely related by evolution

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Three domains of living things Some scientists prefer to classify living things into

domains rather than kingdoms These scientists group organisms according to what

their DNA (genes) looks like Three domains

1. Archaea: Bacteria that live in extreme environments (hot springs)2. Eubacteria: common bacteria3. Eukarya: organisms whose DNA (genes) is in a nucleus

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