Classifying Organisms

Essential Questions• What methods are used to classify living things into

groups.• Why does every species have a scientific name?

• is the process of grouping things based on their similarities.

• Biologists use classification to organize living things into groups so that the organisms are easier to study.

• There are many different ideas about how to classify living things.

Classification

• The first scientist to develop a classification system was Aristotle.

Early Classification Systems

Animals Plants

Presence of “red blood”?

Structure?

Environment? Size?

Shape and size? Tree, shrub or herb?

384-322 B.C.

Determining Kingdoms• Carolus Linnaeus classified organisms based

on similar structures into two main groups called kingdoms.

• After discovering and learning about new organisms, an American biologist proposed a five kingdom system for classifying organisms.–Monera, Protista, Plantae, Fungi, and

Animalia

Determining Domains• Classification system of living things is

constantly changing.• The current method used for classifying

organisms is called systematics. It uses all the evidence known about the organism to classify them.–Cell type, habitat, how it obtains food and

energy, structure and function of features, common ancestry, and DNA.

Using Systematics• Organisms are now split into three domains –

Bacteria, Archaea, and Eukarya.• They are then placed into one of the six kingdoms.

Binomial Nomenclature is the naming system for organisms in which each organism is given a 2 part name (Ex. Ursus arctos)- The first part of the name is the genus.

-group of similar species- The second part of the name is the species - group of organisms that have similar traits and produce fertile offspring.

- usually describes the organisms behavior or appearance.

Scientific Names

Levels of OrganizationSimilar species are grouped into one genus.Similar genera are grouped into one family.Families into orders, then classes, phyla,

kingdoms, then finally domains.From broadest to most specific:

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

Classification Tools• A dichotomous key is a series of descriptions

arranged in pairs that lead the user to the identification of an unknown organism.

Classification Tools• A cladogram is a branched diagram that shows

the relationships among organisms, including common ancestors.

Recap: 3 Domains –

Domain Archaea, Domain Bacteria, Domain Eukarya

These Domains can be further broken

down into 6 Kingdoms

Six Kingdoms

Archaebacteria• Single-Celled Organisms (Microscopic)• Lacks organized nucleus and other organelles.

– Prokaryotic

• Autotrophs and Heterotrophs

• “Archaea” – ancient – lives in extreme conditions

Eubacteria• Single-Celled Organisms (Microscopic)• Lacks organized nucleus and other organelles.

– Prokaryotic

• Autotrophs and Heterotrophs

• “Eu” – new– Different chemical makeup

Protist• Mostly Single-Celled Organisms

– Some are Multicellular

• Organized Nucleus and Organelles (Eukaryotic)

• Autotrophs and Heterotrophs

Fungi• Mostly Multi-celled Organisms (Eukaryotic)

– Some are One-Celled

• Heterotrophs

YeastMold Spore

Mushroom

Plant• Multi-celled Organisms• Autotrophs

– Photosynthesis

• Eukaryotic– Cell Wall and Cellulose

Animal• Multi-celled Organisms• Heterotrophs• Eukaryotic