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Chapter 17Organizing Life’s Diversity

Section 2

The Six Kingdoms

Eubacteria

Contains about 5,000 species

Organisms in this kingdom: Are prokaryotic

(Review: cells lack distinct nuclei bounded by a membrane)

Are microscopic

Are unicellular

Have very strong cell walls

Have less complex genetic make-ups than archaebacteria or eukaryotes

Live in most habitats as long as they are not extreme

Are relatively harmless or helpful (although some can cause diseases)

ARCHAEBACTERIA Contains several hundred species Organisms in this kingdom:

Mostly live in extreme environments that lack oxygen Are prokaryotic Are microscopic Are unicellular Can be heterotrophs or autotrophs

(Autotrophs can be photosynthetic or chemosynthetic)

Have distinct differences from eubacteria and eukaryotes in the lipids of their cell membranes, the composition of their cell walls, and the sequence of the nucleic acids in their ribosomal RNA

Contains very diverse organisms that share some characteristics

Organisms in this kingdom: Are eukaryotic Lack complex organ systems Live in moist environments Have existed on Earth for up to 2 billion years Can be unicellular or multicellular Can be similar to plants, animals, or fungi

Protista

Contains more than 50,000 known

species Organisms in this kingdom:

Are eukaryotic Can be unicellular or multicellular Are heterotrophs (absorb organic materials in

their environment or eat other organisms) Do not move from place to place First appeared in the fossil record over 400

million years ago

Fungi

Plantae

•Contains more than 250,000 known species•Organisms in this kingdom:• Are multicellular• Are eukaryotic• Are photosynthetic•Do not move from place to place•Have cells that usually contain chloroplasts•Have cell walls composed of cellulose•Have a complex cellular organization (tissues, organs, organ systems)• Appeared in the fossil record more than 400 million years ago (but may be much older as they do not have hard parts to fossilize)

Animalia

Organisms in this kingdom:Are eukaryotic

Are multicellular

Are heterotrophic

Do not have cell walls

Are almost all able to move from place to place

Have complex organization (cells, tissues, organs, organ systems)

First appeared in the fossil record about 600 million years ago