week 8 Flashcards
Symbiosis? what is typically seen?
- stable association of two or more organisms (host and symbiont), beneficial, neutral or negative impact
- Genomic reduction typical in symbiotic relationships (genome gets very large and will start to cut costs to save energy)
faculitive and obligatory?
Facultative (aid each other - preferable but not required ) or obligatory (entirely independent - required )
mutualism?
- usually obligatory; both partners benefit from each other
coevolution
evolved together - partners cannot grow without each other
what are 4 examples of mutaulaism?
- buchnera aphidicola and aphids - microbes get a secure habitat and the host gets AA absent in the sap
- termites and protists - termites feed on cellulose and lignocellulose (can not digest on their own so protest helps)
- Coral holobiont - protest gives fixed-c for nitrogenous compounds bc worm lacks digestive track to make C
- rumen ecosystem in cows - breaks down plant matter for the cow and gets food/home from cow
cooperation?
- non-obligatory - not needed for survival
what are examples of cooperation?
- nematode and nematophilia - bacteria live inside and kill insects ,and nematode gives home
- fungal highway - hyphae grow toward nutrients and bacteria move along the surface to explore the environment
- Lichens - mycobiont (fungi provide water and minerals) and photobiont (algae/cyanobacteria provides oxygen)
antagonism? three types
- one organism negatively impacts another
1. predation
2. parasitism
3. competition
what is predation? two strategies used?
- killing - benefits after the victim is killed
1. Epibiotic predators - attach to preys surface and lyse to release preys cytoplasmic contents (Vampirous lugosii - sucks contents. & micrococcus xanthus - consumes organic mater from dead organisms )
2. Endnobiotic predators - invade victims’ cytoplasm, where they consume contents to get energy. (bdellovibrio)
Competition? Two possible outcomes?
- uneasy truce between microbes - Different organisms try to acquire the same resources
1. Contact-independent growth inhibition - carried out by secretions of diffusible compounds (antibiotics)
2. Contact-dependent growth inhibition - physical proximity for toxin delivery
parasitism? benfits? gains what?
- exploitation
- Benefits while the victim is alive
- It can involve nutrient acquisition, physical maintenance, or both
syntrophy? example
- when one species benefits from the metabolic products of another
- Example - Methanotrophic archaea grow in association with sulfate-reducing bacteria
– The archaea consume methane and produce by-products that the bacteria use, while the bacteria help the archaea by removing these by-products, benefiting both organisms
what are the two ways bacteria defend themselves against viruses?
- Restriction modification - chemically distinguish viral and host DNA and hydrolyses viral DNA
- CPISPR/Cas system - recognizes viral DNA by comparing samples from previous encounters to identify and degrade viral genomes
what are communities dependent on?
Energy source (nurteint)
Terminal electron acceptor
Sunlight
what state does water exist in? what are they considered as?
- dissolved
- Microbial versatility = consumption/use of variety of molecules
carbon cycle ? what can it be reduced into? found where? release off? fraction ? global?
- carbon is continuously transferred from one to another
- Plants and microbes fix CO2
- CO2 can be reduced anaerobically to methane, which itself can be oxidized
- Methane can be found in rice paddies, coal mines, etc
- Release of CO2 and biomass production
- A small fraction of decomposed plant material remains in the soil as SOM
- Balancing global CO2 levels, minimizes climate change
nitrogen cycle: Nitrogen fixation? carried out by? ratio? affects?
- reduction of inorganic N2 to organic form (ammonia)
- Carried out by some bacteria and archaea
- It can be carried out under both oxic and anoxic conditions
- Carbon to nitrogen ratio is important for soil quality
- It affects plant growth, microbial activity, and decomposition
Denitrification
nitrate to nitrogen gas
retunes nitrogen to the atmosphere
N availability in ecosystems -> plant growth and agricultural
phosphorus cycle
required in? excess released in? moves to? nutrints?
- Phosphorus is required for ATP, nucleic acids, lipids, and polysaccharides.
- Commonly short supply in soils dependent on soil pH
- When the soil has bound all phosphorus, the excess is released by soil erosion
- Moves to lakes, streams, and estuaries where it can stimulate the growth of microorganisms
- Nutreninet availability and microbes in soil and water
- Binding to soil depend on soil pH
sulfur cycle
reduction?
depending on?
?->?
- Reduction of sulfate for use in amino acids and protein biosynthesis
- depending on the oxidation of Sulfur species, it can serve as electron donors and acceptors or both
SO4^2- -> H2S in anaerobic (dissimilatory sulfate reduction)
iron cycle
- used in?
- important for?
- element ?
- avalibility for?
- respiration/photosynthesis
- Fe3+ can serve as a terminal electron acceptor during anaerobic respiration in a range of bacteria and archaea (redox reaction)
- Iron availability to plants and algae
maganese cycle
Mn2+ as an electron donor —- reduction(anoxic) ——> MnO2 e- acceptor
<—– oxidation (oxic)
mercury cycle
biomagnifcation?
reduction?
does?
- Biomagnification - anaerobic bacteria feed into the food chain and accumulate
- Demethylation of methylmercury -> Hg^0/reduction
- Microbes can either facilitate toxic transformations or detoxify mercury/preventution of bioaccumilation
Greenhouse gases?
- trapped heat reflected from earths surface in the atmosphere, rather than allowing it to radiate into space
- Gases accumulate if the rate they enter the atmosphere exceeds the rate by which the natural carbon and nitrogen cycle can remove them