Prokaryotes Flashcards
When were archaea discovered?
1970s with RNA sequence data
What’s the most importatnt difference between Bacteria and Archaea?
Bacteria have peptidoglycan in cell wall, but Archaea don’t
Prokaryotic cell structure
- unicellular
- no nucleus or membrane bound organelles
Bacterial cell wall
- G+ has thick peptidoglycan
- G- has thin peptidoglycan and outer lipopolysacchride membrane
Bacterial flagella
- different from other flagella
- circular motor spins
Spirochetes
- Have internal flagellum (axial filament) that runs between cytoplamic and outer membrane
- mostly free living and anaerobic
- some are pathogens (syphilis and lymes)
- chemoheterotrophic
Chlamydias
- live only as intracellular parasites
- aerobic
- G- cocci
- one of the smallest prokaryotes
- small genome : 1-1.3 megabases
- Elementary Bodies are infective and Reticulate bodies replicate in cells
- very little peptidoglycan –> don’t stain, but are still sensitive to penecilin
Hyperthermophilic Bacteria and Hadobacteria
- G- and sometimes high GC content
- not monophyletic
- best above 80C some can survive above 122C
- Aquifex = chemoautotrophs living in volcanic vents and hot springs (similar to archaea)
- Deinococcus = resistant to radiation –> used in bioremediation of toxic waste sites
- Thermus aquaticus = sourse of DNA polymerase used in thermocyclers (TAQ)
Actinobacteria
- Filamentous (fungi like)
- Not all have high GC content
- Streptomyces are sources of antibiotics
- Myobacterium tuberculosis and M. Leprae
- Typically G+ and non spore forming
- some have mycolic acid
- important decomposers in soil
- mostly aerobic
Firmicutes
-Includes Bacilli (aerobic) and Clostridium (not)
-Gram positive
Staphylococcus and Streptococcus
-Heliobacteria = anaerobic, photoheterotrophic N-fixers
-Mycoplasmas = tiny obligate parasite with no cell wall because it can’t make peptidoglycan –> steals sterols from host for membrane
Cyanobacteria
- Most diverse and ecologically successful group of bacteria
- exists in all terrestrial and aquatic habitats
- big, multi-shaped, G+
- Blue bc of pigments (phycocyanin)
- uses chloryphyll a
- some fix nitrogen
- ancestor of chloroplast
Proteobacteria
- Gram negative
- Super diverse (like proteus)
- N-fixing soil bacteria
- usually anaerobic
- alpha proteobacteria = mitochondria origin
- ancestor was probably photoautotrophic
- tons of human pathogens
Photoautotrophic purple bacteria + relatives are anoxygenic and anaerobic and they use bacteriochlorophyllls instead of chlorophyll a
Other bacteria phylum
bacteriodetes synergistetes chrysiogenetes thermodesulfobacteria fusobacteria acidobacteria deferribacters thermotogae nitrospirae chloroflexi dictyglomi
When/who discovered archaea
1970s Carl Woese
Do archaea form spores?
no
