Chapter 19 Peptidoglycan cross linked polymer of amino sugars that produces mesh like structure around cell unique to bacteria seperates archaea and bacteria Gram positive bacteria blue purple thick peptidoglycan layer Gram negative bacteria pink red thin peptidoglycan wall Bacteria shapes coccus spherical bacillus rod spirillus spiral Low GC Gram pos Low less than 50 G C to A T nucleotide pairs in DNA Produce endospores heat resistant resting structures High G C Gram pos higher ratio of G C to A T nucleotide pairs reproduce by forming chains of spores of tips of filaments most antibiotics come from high G C gram pos Hyperthermophilic bacteria extremophiles used to be thermophiles Hadobacteria Cyanobacteria thermophilic extremophiles Blue green bacteria because of pigmentation phtosynthetic bacteria can differentiate into three types vegetative cells photosynthesize spores resting stages that survive harsh environments and develop into filaments Heterocysts fix nitrogen Spirochetes Chlamydias Gram neg motile bacteria characterized by axial filaments modified flagella Cell body long cylinder coiled into helix only parasites gram negative can take ATP from hosts life cycle involves two different forms of cells elementary and reticulate bodies Proteobacteria Some N fixers largest group of bacteria many gram neg photoautotrophs Archaea two groups crenarchaeota and Euryarchaeota absence of peptidoglycan and presence of distinctive composition in cell membranes many extremophiles Many microbial communities tend to form dense biofilms biofilms sticky gel like polysaccharide matrix that traps other cells Obligate anaerobes oxygen sensitive organisms Facultative anaerobes prokaryotes that can shift between anaerobic and aerobic modes Aerotolerant anaerobes can t conduct cellular respiration but not damaged by oxygen when present fix carbon Obligate aerobes unable to survive in absence of oxygen Photoautotrophs perform photosynthesis Photoheterotrophs use light as energy source but must obtain carbon atoms from organic compounds made by other organisms Chemolithotrophs energy obtained by oxidizing inorganic substances and use some energy to Chemoheterotrophs energy and carbon atoms from one or more complex organic compounds that have been synthesized by organisms Denitrifiers give back nitrogen gas to atmosphere Nitrifiers convert nitrogen so plants can use Bacteria evolve through lateral gene transfer and gene duplication