A RCHAEBACTERIA E UBACTERIA

A RCHAEBACTERIA Major Characteristics Generally only live in very harsh environments, such as those w/o O 2 —also known as extremophiles because they can survive pressures over 200 atm Microscopic: diameters between inches Cell Type: prokaryotes (DNA not enclosed in nuclei) Cell Structure: similar to bacteria but different chemical composition in cell wall & cell membrane, few internal organelles Body Plan: unicellular

A RCHAEBACTERIA Metabolism: autotroph or heterotroph Reproduction: asexual (binary fission) 4 major Phyla: Crenarchaeotes: live in hottest, most acidic environments Kararchaeotes: newly discovered in Yellowstone, may be least-evolved lineages of modern life Nanoarchaeotes: one species exists, relatively unknown, smallest genome of any organism Euryarchaeotes: very diverse group

A RCHAEBACTERIA Some live in environments that are so harsh pressures reach 1 ton/cm 2

E UBACTERIA Major Characteristics Differ from archaebacteria by chemical composition Are vital in recycling nutrients Grow in all environments, from guts of animals to soil and radioactive waste Cell Type: prokaryotes Cell Structure: variety of cell shapes: sperical, rodlike, spiral; few if any internal organelles, some have external flagella Body Plan: unicellular

E UBACTERIA Metabolism: autotroph or heterotroph Reproduction: asexual (binary fission) 4 major Phyla: Proteobacteria: includes E. coli and nitrogen-fixing bacteria in soil Spirochaetes: distinctive spiral shape; some cause syphilis and Lyme disease Actinobacteria: many soil bacteria belong here; some produce antiobiotics (streptomycin), some produce harmful illnesses: anthrax, tetanus, botulism; one produces a powerful insecticide used for genetic engineering in plants Cyanobacteria: photosynthetic; among oldest organisms on Earth; are key sources of C and N in the environment