Classification 2

MBI 121September 19, 2012

Fungi

• Diverse Kingdom• Single cell / multicellular• All are heterotrophic• Produce “exoenzymes” &

spores (not same as bacteria)

• Yeast, mushrooms, molds, lichens

Important roles of fungi

• Decomposers• Symbiotic relationship w/plants• Bread, wine, beer, antibiotics• Similar to animal cells– “model” organisms

Yeast - single cell fungi• Crucial to our daily lives - foods• Yeast can use sugar to produce alcohol

– When [O2] drops

• Model system to study genetics, cell division

(See Fig. 8.1)

Mycotoxins

• Many types of fungi produce toxins• Some are helpful (antibiotics)• Some harmful (carcinogenic)• Some deadly (Amanita mushroom)

Penicillin• Discovered by Andrew Fleming in 1929• Produced by Penicillium mold

Aflatoxin• Produced by Aspergillis• Causes cancer w/chronic low dose• Liver failure w/high dose

Amanita phalloides

• “Death cap”• 5-24hrs nausea, vomiting,

diarrhea• 2-3 days feel better• Liver & kidney failure

Animal pathogens

• Many fungal infections are opportunistic• Candida• Cryptococcus neoformans (birds)

– infection of lungs & meninges– Very dangerous for AIDS, immuno-suppressed

• Very difficult to treat

White Nose Syndrome

75-100% mortality rate Infects while hibernating

Bacteria (& Archaea) are among the most abundant organisms on earth

• Outnumber eukaryotes• Outweigh eukaryotes• Diverse environments– Metabolically diverse

• ID’d ~2% of total species on Earth• Cyanobacteria

Based on 16S rRNA sequence

Thermophiles

• Grow & thrive at 95o C and above• “primitive cells” – most similar to early life?

D. radiodurans

• Extremely R to radiation• Survive 3 million rads• Humans die if exposed

to 500 rads• Repairs DNA at extreme

rate

Based on 16S rRNA sequence

Spirochete – one causes syphilis

Proteobacteria

• Large, varied group of Gram neg species

• E. coli best known

Domain Archaea

• Originally identified “extremophiles”

• Live in hyper-saline environments• Methanogens – produce methane– biofuel

• Extreme heat• Some live in ocean and in your

mouth, though!