biology 121: diversity, structure and function fall 2010 sonoma state university tom buckley 08 sep...
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Biology 121: Diversity, Structure and Function
Fall 2010Sonoma State University
Tom Buckley08 Sep 10
Prokaryote diversity and metabolism
Prokaryotes: 90% of all biomass on Earth
Two major groups: Bacteria and Archaea
Prokaryotic phylogeny
Archaea extremophilesdiverse metabolism
Bacteria familiar prokaryotesmany pathogens
Prokaryotic cells
0.5 - 5 m diameter
Staphylococcus (strep throat)
Escherichia coli (E. coli)
Borellia burgdorferi (lyme disease)
examples
Q: what is 1 m in terms of millimeters?
Prokaryotic cell surfaces
Bacteria: two groups
Gram-positive Gram-negative: double membrane
Archaea: no peptidoglycan'Gram stain'stains peptidoglycan
Prokaryotic cell surfaces
capsule:sticky polysaccharides
Streptococcus tonsil tissue
protects againstphagocytosis & detergents
phago- = eatcyto = cell
Internal structure
(Heterotrophic) (Autotrophic)
Prokaryotic DNA
Much less DNA than eukaryotes
Organised in circularchromosomes
one very large loop
+ numerous very small ones (plasmids)
Plasmids in biotechnology
Cut plasmid withrestriction enzyme
Add DNA fragment w/new gene
Plasmid recombinesw/ fragment
Infect plant cellsw/ bacterium
Q: which plant cells should you infect?
Prokaryotic reproduction
Binary fission identical copy
Conjugation: one-way DNA transfer
Prokaryotic reproduction
Fission every 20 min - 24 hours
How long would it take to produceenough bacteria to reach the sun?
bacterium: 2 m longfission rate: every 3 hourssun distance: 150 million km
Prokaryotic reproduction
Short generation times
Frequent mutation
Huge population sizes
Strong selection
Extremely fast evolution
Prokaryotic evolution: example
grew bacteria in low-glucose solutions
periodically compare fitness against ancestral population
RESULT
Prokaryotic evolution: example
grew bacteria in low-glucose solutions
periodically compare fitness against ancestral population
Possible interpretation...
ancestral populationalso evolved
Control to rule this out...
RESULT
answer in class
something else in the solutionfavoured the new population
answer in class
Metabolism
Metabolism
MetabolismFood = electron donorNADH = electron carrierO2 = electron acceptor
Metabolism Aerobic respiration
CO2 CH2O
ATP ADP
energy
electrons
O2H2O
oxidation
ATP ADP
MetabolismFood = electron donorNADH = electron carrierO2 = electron acceptor
Aerobic respirationAnaerobic respiration
CH2O
ATP ADP
energy
O2H2O
lactate orethanol + CO2 CO2
CH2O
ATP ADP
energy
electrons
O2H2O
ATP ADP
x
oxidation
ATP ADP
Aerobic respirationPhotosynthesis
CO2 CH2O
oxidation
ATP ADP
energy
electrons
O2H2O
ATP ADP
CO2 CH2Oreduction
solarenergy
electrons
O2H2O
ATP ADP
Aerobic respirationPhotosynthesis
CO2 CH2O
oxidation
ATP ADP
O2H2O
CO2 CH2Oreduction
O2H2O
Prokaryotic metabolism: diversity
Prokaryotic metabolism: ecology
1. Nitrogen fixation
NH3
organic N
N2
1
2. Ammonification
organic NNH32
NO3
3. Nitrification
3
4. Denitrification
NOx
4
4
Nitrogen fixation (requires anaerobic conditions)
Prokaryotic metabolism
O2
N N
Nitrogen fixation (some plants)
Prokaryotic metabolism: symbiosis
Gut digestion (many animals, incl. ruminants & humans)
legume family (beans)many others
nodules
Prokaryotic metabolism: ecology
1. Nitrogen fixation
NO3
3. Nitrification
4. Denitrification
NOx
NH3
organic N
N2
1
2. Ammonification
organic NNH323
4
4
Q: What would happen to atmospheric N2
without N-fixing prokaryotes?
Prokaryotic metabolism: ecology
1. decomposition
CO2
organic C
organic C1
Q: What would happen to atmospheric CO2
without decomposing prokaryotes?
2. photosynthesis
3. death/senescence
2
3
Biotech
Prokaryotes: relevance to humans
Gut digestion
Pathogens
Ecology & agriculture:
decomposition (C & N cycling)
bioremediation (many pollutants)
synthetics (plastics, ethanol)
rapid evolution --> antibiotic resistance