Viruses and Prokaryotes Chapter 20 Viruses and Prokaryotes

Prokaryotes Unicellular, auto- or hetero- troph, no nucleus Reproduce by binary fission Conjugation – how bacteria exchange genetic info

Domain Archae - Kingdom Archaebacteria - walls lack peptidoglycan - DNA more similar to eukaryotes - live in extreme environments

3 types of Archaebacteria 1. Methanogens – produce methane gas, most anaerobic 2. Extreme halophiles – in high salt areas; use it to make ATP 3. Thermacidophiles – in high temps and acidic areas

Domain Bacteria - Kingdom Eubacteria - walls with peptidoglycan - larger domain - found everywhere

Eubacteria - grouped by 2 things 1. shape: - bacillus – rod - coccus – spherical - spirallus – spiral, corkscrew

2. Response to Gram Stain: - Gram positive – purple, retains stain; thicker layer of peptidoglycan - Gram negative – pink, doesn’t retain stain; thinner layer of peptidoglycan; unaffected by many antibiotics

Importance Decomposers Producers Nitrogen fixation Human uses – foods, break down wastes and poisons in water, produce drugs, etc