Classification of Living Organisms

Classification

Grouping organisms by similar structures and functions.

Domains

Three major categories: Bacteria, Archaea, Eukarya.

Kingdom

Most inclusive group in Linnaean hierarchy.

Phylum

Second level in the taxonomic hierarchy.

Class

Third level in the taxonomic hierarchy.

Order

Fourth level in the taxonomic hierarchy.

Family

Fifth level in the taxonomic hierarchy.

Genus

Sixth level in the taxonomic hierarchy.

Species

Seventh level; most specific classification.

Binomial Nomenclature

Two-part naming system for organisms.

Linnaean Hierarchy

System of classification developed by Linnaeus.

Two Kingdom System

Linnaeus's initial classification: Plantae and Animalia.

Five Kingdom System

Proposed by Whittaker; includes Monera, Protista, Plantae, Fungi, Animalia.

Prokaryotes

Single-celled organisms without a nucleus.

Eukaryotes

Organisms with complex cells containing a nucleus.

True Bacteria

Group of prokaryotes classified under Domain Bacteria.

Archaea

Prokaryotes distinct from true bacteria.

Photosynthetic Protists

Eukaryotic organisms capable of photosynthesis.

Taxonomic Hierarchy

Levels of classification from general to specific.

rRNA Comparisons

Method used by Woese to classify prokaryotes.

Distinguishing Characteristics

Traits used to differentiate domains and kingdoms.

Evolutionary Relationships

Connections between organisms based on common ancestry.