Unit 11: Classification of Living Things

Tacitus bellus

Populus tremuloides

Quaking Aspen

Finding Order in Diversity• To study the diversity of life,

biologists use a classification system to name organisms and group them in a logical manner.

• Taxonomy is the branch of biology that groups and names organisms based on studies of their different characteristics.

• Biologists who study taxonomy are called taxonomists.

• Classification systems change with expanding knowledge.

Carolus von Linnaeus(1707-1778)

Carolus Linnaeus• Swedish botanist• Developed Binomial

Nomenclature• Two-word naming system

– Genus» Noun, Capitalized,

Underlined or Italicized– Species

» Descriptive, Lower Case, Underlined or Italicized

– Each species is assigned a two-part scientific name

» Ex. Ursus arctos

System of Classification• Linnaeus’s hierarchical system of

classification includes eight levels (from largest to smallest)

• Grizzly Bear (common name)– Domain Eukarya– Kingdom Animalia– Phylum Chordata– Class Mammalia– Order Carnivora– Family Ursidae– Genus Ursus– Species arctos

Each of the levels is called a TAXONUrsus

arctos(scientific name)

System of Classification• Taxonomic categories, an

acronym:– Domain Dear– Kingdom King– Phylum Phillip– Class Came– Order Over– Family For– Genus Good– Species Soup

KKPPCCOOFFGGSS

Use the table to complete the worksheet

WorksheetWorksheet

• Phylogeny – evolutionary relationships among organisms

• Evolutionary classification – strategy of grouping organisms together based on their evolutionary history– Fossil record– Comparative homologies– Comparative sequencing of

DNA/RNA among organisms– Molecular clocks

Evolutionary Classification

Molecular Clock

Allows scientist to compare DNA sequences form two species to estimate how long it has been since they diverged from a common ancestor

Taxonomic Diagrams

Phylogenetic Tree: Represent hypothesized evolutionary relationships

Mammals Turtles Lizards and Snakes Crocodiles Birds

Looks like aBranch on a

tree

Attempt to trace the process of evolution by

focusing on shared features

Mammals Turtles Lizards and Snakes Crocodiles Birds

CladogramTaxonomic Diagrams

Which organism is the outgroupMammals

Which 2 organism are more closely related

Crocodiles and birds

Refer to page 496 to 497WorksheetWorksheet

Dichotomous Keys Identify Organisms • Dichotomous keys contain pairs of

contrasting descriptions.• After each description, the key directs

the user to another pair of descriptions or identifies the organism.

Example: 1. a) Is the leaf simple? Go to 2b) Is the leaf compound? Go to 32. a) Are margins of the leaf jagged? Go to 4b) Are margins of the leaf smooth? Go to 5

WorksheetWorksheet

Classification of Living Things

Domains (Notice the domains on the chart)

• Most inclusive category • Larger than a kingdom• There are 3

– Eukarya – includes the kingdoms»Protists, Fungi, Plants &

Animals– Bacteria – corresponds to the

kingdom Eubacteria– Archaea – corresponds to the

kingdom Archaebacteria

Slides 17-23

•Is more specific with the classification

Kingdoms• (Eubacteria and Archaebacteria)

Prokaryotes, with or without peptidoglycan in cell walls

• Protista – Eukaryotes, diverse, not fungi, plants, or animals

• Fungi – Eukaryotes, multicellular (except yeasts), heterotrophic, chitin in cell walls

• Plantae – Eukaryotes, multicellular, autotrophic, cell wall containing cellulose

• Animalia – Eukaryotes, multicellular, heterotrophic, no cell wall

Kingdom - Eubacteria• Common name: Bacteria• Unicellular prokaryotes• Peptidogylcan in cell wall• Ecologically diverse • Basic shapes are cocci,

bacilli, spirilla• Reproduce both sexually and

asexuallyBacillus anthracis(spores can live in

soil for years)

Streptococcus mutans

(can cause endocarditis and

dental caries)

Kingdom - Archaebacteria• Cell wall does not contain

peptidogylcan• Cell membrane contains unusual

lipids not found in other organisms• Live in extreme environments

(devoid of oxygen):– volcanic hot springs– brine pools– black organic mud

Archaeafirst detected in

extreme environments,

such as volcanic hot springs.

Kingdom Protista• A classification problem – consists of

organisms that cannot be classified as animals, plants, or fungi

• Most unicellular, some colonial and some multicellular

• Autotrophic and heterotrophic• Some move with flagella,

pseudopods or cilia• Animal-like, plant-like and fungus-

like groups• Reproduce by mitosis and meiosis

Entamoeba histolytica

Kingdom Fungi• Most feed on dead, decaying

organic matter by secreting digestive enzymes into their food source then absorbing it into their bodies

• Cell walls of chitin• Most multicellular; some

unicellular• Heterotrophic

Boletus zelleri(Edible, but often infected with fly

larvae)

Epidermophyton floccosum

(one of the causes of

athlete's foot)

Kingdom Plantae• Multicellular• Nonmotile – cannot

move from place to place

• Cell wall with cellulose• Mostly photosynthetic

autotrophs

Sunflowers in Fargo, North

Dakota

Ginkgo bilobaGinkgos are often very long-lived.

Some specimens are thought to be more than 3,500

years old.

Kingdom Animalia• Multicellular• Heterotrophic• No cell walls or

chloroplasts• Incredible diversity

Chambered

Nautilus

Colony of sponges

Hymenoptera Dialictus zephrum

Txodes scapularisDeer tick

Hierarchical Systemof Classification

Domain

KingdomPhylum

ClassOrder

FamilyGenus

Species• From general to more specifi

c

How Many Kingdoms?

6Kingdoms

•Activity: What am I?