Unit 4: Chapter 28 Flashcards
_________ increasing mating season for mosquitoes that carry disease causing microbes
Warmer temperatures
Increased temperature is caused from
climate change
Biogeochemical cycling
Sum of microbial, physical, and chemical processes that drive the flow of elements with influx of nutrients from one pool to another
Flux
nutrients move between pools and are chemically modified
Abiotic processes
Nonliving
Ex. Erosion
Biotic processes
Living and refers to nutrient cycling
Nutrients refer to
chemicals (inorganic and organic)
Nutrient cycling is performed by
bacteria, archaea, and eukaryotic microbes
Microbes on Earth’s surface contribute to
rapid nutrient cycling
Microbes on very slow growing deep surface contribute to
elemental cycling over geological periods
What if all prokaryotes suddenly vanished from Earth suddenly?
No one can live since nutrient cycling and biochemical cycling will be shut down
Redox potential
measure of the tendency of molecules in a system to accept or donate electrons
Redox potential is determined by the electrical potential difference betweeen ___ and ________
environment; standard hydrogen electrode
Redox potential is expressed in
volts or millivolts
Low redox potential
Readily donate electrons
High redox potential
Readily accept electrons
Redox state of environment plays a critical role in
determining the types of microbes present
Redox stae of environmental determines the types of microbes by:
- which oxidized compounds are available as terminal electron acceptors
- what reduced molecules are present for use as electron donors
What influence the availability of terminal electron acceptor?
Redox potential, pH, and oxygen concentration
______ declines with depth in water and soil
Oxygen concentration
ΔG°’ negative indicates
exergonic, more free energy released
ΔG°’ positive indicates
endergonic, less free energy released
More positive value of ΔG°’ indicates
less energy released and more in depth
What processes provide greatest amount of energy?
Aerboic respiration
Which processes provide least amount of energy?
Methanogenesis by Archaea
Reduced form
Gaining electrons and H+, lose O2
Oxidized form
Losing electron and H+, gain O2
What elements contain intermediate oxidation state forms?
Carbon, nitrogen, sulfur
What elements do not contain intermediate oxidation state forms?
Iron, phosphate, maganase
Fate of organic materials:
Minneralization and Immobilization
Minneralization
decomposition of organic matter to simpler inorganic compounds (O2, NH3, H2,..)
may or may not be recycled
Immobilization
nutrients converted into biomass become temporarily unavailable for nutrient cycling
____ are important in mineralizing immobilized organic compounds
Saprophytes
What elemnt is most abundant?
Carbon
____ is continously transformed from form to another
Carbon
CO2 is reduced to
methan (CH4)
Methanogenesis
No O2 available (anaerobic)
CO2 reduced to CH4 by methane by archaea
Reverse methanogenesis
Archaea and reducing bacteria work togerther to oxidize methan using sullfate as terminal electron acceptor
Methanotrophy and methylotrophy
O2 available (anaerboic and aerboic)
CH4 oxidized to CO2
CO2 fixation
O2 available (anaerboic and aerboic)
CO2 reduced to organic matter
Phototrophy and Chemotrophy
Oxidative and redox neutral
Aerboic/ Anaerboic respiration and fermentation
Organic matter oxidized to CO2
All fixed carbon enters common pool of organic matter that can be oxidized back to CO2 through
aerobic/ anaerobic respiration and fermentation
Inorganic carnon (CO2) and organic carbon can be reduced _____ to methane
anaerboically
Source of carbon
heterotrophic microbes and burning of fossil fuels release carbon as CO2
fossil fuels and CO
Carbon sinks
plants, phytoplankton, and other autotrophic microbes that TAKE UP CO2 from atmosphere
Carbon reservoirs
STORE carbon for geological periods of time
Methane oxidized ___ by bacteria or _____ by archaea
Aerboically, anaerboically
_______ found in rice paddies, ruminant animals, coal mines, sewage treatment plants, landfills, and marshes
Methane sediments
Degradation of organic matter influenced by several factors including:
- oxidation reduction potential
- availability of competing nutrients
- abiotic conditions (pH, temperaturem O2, osmotic conditions)
- microbial community present
Microorgnaisms secrete hydrolytic enzymmes that degrade ___
Ligin
Microorgnaisms secrete hydrolytic enzymmes that degrade ligin include
Fungi (eukaryotic) and streptomyces (prokaryotic bacteria)
Microorgnaisms that degrade ligin only contain
carbon, hydrogen, oxygen
Microorgnaisms that degrade ligin must
acquire remaining nutrients
Limiting nutrient
nutrient that is insufficient for maximal growth
Nitrogen exists in redox states from
-3 to +5
Nitrogen species serve as electron acceptor in ____ or as electron donor in ______
anaerboic respiration; chemolithotrophy
Nitrogen fixation
N2 gas reduced to NH3
Nitrogen fixation is carried out by
some bacteria and archaea
oxic and anoxic conditions
What bacteria involved in nitrogen fixation under oxic conditions?
Clostridium
Product of nitrogen fixation is
Ammonia (NH3)
Bacteria which help with nitrogen fixation
Azotobacter
Clostridium
Rhizobiales
Cyanobacteira
Assimilation
NH3 converted to organic N
Taken up by plants and animals
Mineralization in nitrogen cycle
Organic N reduced NH4+
Commanox
NH4+ oxidized to NO3- (nitrate) in 1 step by mitrospira
Mitrospira
bacteria that helps commanox
Nitrification
NH4+ oxidized to NO3- in 2 steps
NH4+ –> NO2-
NO2- –NO3-
In Nitrification __ donates electron
Ammonium (NH4+)
NH4+ in nitrification is e- donor or e- acceptor
e- donor
reduced form
NO3- in nitrification is e- donor or e- acceptor
e- acceptor
oxidized form
Assimiliary nitrate reduction
NO3- is reduced to NH4+ and taken up by organisms
Incorporated into microbial and plant cell biomass
Dissimilary nitrate reduction
NO3- (nitrate) is used as terminal e- acceptor during anaerobic respiration and reduced to N2 (nitrogen gas)
NO3- –> N2
Nitrogen is removed from cytoplasm and returned to atmosphere
Ammanox
NH4+ reduced to N2 with NO2 as terminal e- acceptor
Shortcut to produced N2 gas without going to nitrate
Anaerboic!
Denitrification
loss of nitrate by process of anaerboic respiration of soil bacteria
occurs in flooded/ waterlogged soils
Converts nitrate into gaseous nitrogen that enters atmosphere and represents considerable economic loss
Why is denitrification a problem for farmers?
Loss of nitrogen and comverts into gaseous nitrogen to atmospheric
ECONOMIC LOSS
Phosphorus in nature exist as
Phosphate ion PO43-
Phosphorus is required for
ATP, nucleic acids, lipids, polsaccharides
Source of phosphorus
Weathering of phosphate containing rocks
Eutrophication
Phosphorus and nitrogen are suddenly too abudant (too many nutrients) and promote growth of algae bloom in water
_____ is not abudant and is limiting nutrient which limit growth of organism
Phosphorus
Cause of eutrophication
Phosphorus in run off water
Depending on oxidation state of sulfur species it can serve as
e- aceptor, e- donor, or both
____,_____, and ______ are abudant in detergent and fertilizer
phosphate, phosphorus, and nitrogen
Some organisms can use ___ as carbon energy source
sulfur
Dissimalatory sulfate reduction
Use of sulfate as terminal e- acceptor where organsism die and degraded by saprophytes to return sulfate back into environment
Assimilary sulfate reduction
Sulfate (fully oxidized) is reduced by plants and microbes for use in amino acid and protein synthesis
In dissimalatory sulfate reduction, resulting ____ is not taken up for use in _____
Ferrous iron (Fe2+); cellular biosynthesis
assimiliate in reference to nitrogen and sulfur use means:
take in so nitrate and sulfate used for growth
______ forms can not be incorportaed directly into organic molcules so it must first be ____ through process _________
oxidized, reduced, assimilatory reduction
Dissimilatory reduction in reference to nitrogen and sulfur use means:
using nitrate or sulfate as e- sink
resulting reduced compound is NOT taken up by microorganism
Sulfur cycle resembles ___ cycle
phosphorus
Why does the sulfur resemble the phosphorus cycle?
Sulfur is mostly in solid form
Orginates from natural sedimentary deposits in rocks, oceans, lakes, and swamps rather than atmosphere like nitrogen
_____ is essential elemt in very small quantities
Free iron
___ is transfered into the cell in iron cycle
Fe3+
Iron often exists in ____ state for uptake
wrong oxidation state
___ bind Fe3+ and faciliate its transport into the cell and is reduced to Fe2+
siderophores
Dissimilatory reduction in iron cycle
Fe3+ serves as terminal e- acceptor during anaerboic respiration
Mganese cycle, transformed reduced ___ to oxidized _____
Mn2+, MnO2
Diverse bacteria use ___ as e- donor with oxygen or ___ as terminal e- acceptor
Mn2+, nitrate
____ molecules link carbon cycle to either nitrogen, sulfur or iron cycle
chemolithotrophic
Biogeochemical cycling is ____ and ____ processes which keep biosphere __________
dynamic, interconnected, self sustaining
Global climate change indicates biochemical cycling is
out of balance
___ is critical in maintaining dynamic equilibrium that defines our biosphere
microbial activity
Global climate change
term that reflects changes in patterns of wind, precipiation, and ocean and atmospheric temperatures that Earth is now experiencing
What are the 3 green house gasses?
Carbon Dioxide (CO2), Methan (CH4), and nitrous oxide (H20)
Greenhouse gases
Trap heat reflected from Earth’s surface rather than allowing it to radiate into space
When do green gasses accumulate?
If rate of gasses enter atmopshere exceeds by which natural carbon and nitrogen cycle can remove them
Accumulation of gasses has resulted in
global warming
What gas contributes the most to global warming?
Methane (CH4)
Methan contributes ___ times global warming potential than CO2
30 times
The consequences of disrupting Nitrogen and Carbon cycle:
Global climate change
Why is methane the most causing greenhouse gas?
Single CH4 has same thermal retention capacity as 30 CO2 molecules
Methan has increased ___ times to present level in last 10 years
2.5
Global climate change is measured over;
decades
Parameters of global climate change is measured by:
- surface temperature on land, sea, atmosphere
- rates of precipitation
- frequency of extreme weather
