Taxonomy & Biological Classification

Taxonomy Basics

• Study of classification of living organisms (taxonomy)
• Each organism given a scientific name via binomial nomenclature $(\text{Genus species})$
• Classification criteria: cell type, number of cells, genetics, mode of nutrition, environment

Taxonomic Hierarchy (Broad ➜ Specific)

• Domain ➜ Kingdom ➜ Phylum ➜ Class ➜ Order ➜ Family ➜ Genus ➜ Species

Domains & Representative Kingdoms

Archaea

• Kingdom: Archaebacteria
• Traits: prokaryotic, unicellular, auto- or heterotrophic
• Habitat: extreme environments (e.g., high salt, heat)
• Example: halobacterium

Bacteria

• Kingdom: Eubacteria
• Traits: prokaryotic, unicellular, auto- or heterotrophic
• Habitat: common/"normal" environments
• Example: $E.\ coli$

Eukarya

• Contains four kingdoms; all are eukaryotic

Protista

• Mostly unicellular; some colonial/multicellular
• Plant-like, animal-like, or fungus-like forms
• Example: amoeba

Fungi

• Mostly multicellular (yeast unicellular)
• Heterotrophic; absorb nutrients from dead/decaying matter
• Cell walls made of chitin

Plantae

• Multicellular, autotrophic via photosynthesis
• Cell walls present (cellulose)
• Examples: mosses, ferns

Animalia

• Multicellular, heterotrophic, motile
• No cell walls; highly complex body organization
• Examples: humans, other animals