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
Lipid of archeae
L-glycerol phospholipids in backbone
ether-linked and branched isoprenoid side chains
stabler than bacteria
What forms of eating can archaea do?
- photoheterotroph, chemoheterotroph, and chemoautotroph
- NOT PHOTOAUTOTROPH
Describe archaea flagella.
Is it similar to the bacterial?
- not homologous
- thinner, solid, and powered by ATPase
T/F all archaea are extremophiles
-false… they can be found in all habitats
Many archaea are infected by host specific viruses. What does this imply about evolution?
-The emergence of certain virus groups preceeded the split of archaea from bacteria
Are archaea the only ones who can perform methanogenesis?
yes
Four superphyla of archaea
- euryarchaeota
- TACK
- DPANN
- Asgard
What were the original two superphyla of archaea
-euryarchaeota and Crenarchaeota
Euryarchaeota
- Methanogens, halophiles, and thermophiles
- some halophiles can use light energy to synthesize ATP
- Halobacterium salinarium
Crenarchaeota
- Part of TACK phyla
- many are strict anaerobes
- usually hyperthermophilic or acidophilic
- seen at Yellowstone or in deep sea volcanoes
- Chemoheterophs or chemoautotrophs
- Important genera = Sulfolobus and Thermoproteus
DPANN
- Many are small with little genomes
- many are symbiotic
Nanoarchaeum equitans
- obligate symbiont of Ignicoccus (archaea)
- takes lipids from host bc can’t make AA, fats, or nucleotides
- smallest known genome
- originally its own phylum bc Nanoarchaeum equtans was discovered in thermal icland vents
Asgard
Lokiarchaeotes
- discovered near hydrothermal vents in arctic ocean 2015
- genome has genes and functions previously thought to be unique to eukaryotes
- more closely related to Eukaryotes than to any prokaryote
Viruses
- part of Tree of Life
- Derived from cellular life forms, but not alive
- Probably evolved in all groups of organisms
- Reconstructing origins phylogenetically is hard
- constantly changing and adapting
