L5 Electron Transport Snd Lithotropy Flashcards
Before electron transfer, the donor is in a … form
Reduced
The donor undegos a … reaction
Oxidation
What is meant by a redox couple
The oxidised and reduced states of a compound
In organotrophy what is the electron donor and what is the terminal acceptor
Organic molecules donate electrons
Oxygen is the terminal acceptor in respiration but there are alternatives (fumarate if anaerobic)
In chemolithotrophy, are electron donors organic or inorganic
Inorganic e.g. Fe2+, H2, H2S
What is the terminal electron acceptor in chemolithotrophy
Oxygen
There are anaerobic alternatives: NO3- and fumarate
What kind of environments are chemolithotrophs likely to be found in and why
Extreme environments as the chemical environment is altered by the chemicals released by microbes
What does Nitrosomonas europaea oxidise
Ammonia
Give 2 roles lithotrophy plays in the encironment
Weathers bedrock to form soil
Nitrogen and sulfur cycling
∆G of a redox reaction is proportional to…
The reduction potential (E) between an electron acceptor and its donor
A positive E means…
Is the ∆G positive or negative
Electrons have been gained
Negative - yielding energy
When talking about redox reactions, is it more likely to see millivolts (E) or Gibbs free energy (G)
Millivolts (E˚)
What happens if E.coli is present in an environment without oxygen
What happens if oxygen becomes available again
If oxygen is absent the electrons are transferred to fumarate
NADH + H+ + fumarate —> NAD+ + succinate
If oxygen returns then succinate is metabolised back into fumarate, again releasing energy
What is ∆p
Proton motive force
How do you calculate proton motive force
∆p = ∆v + ∆pH
∆p - proton motive force
∆v - change in charge (in volts)
∆pH - change in pH (concentration of H ions)
How can the proton motive force be used by the cell
ATP production
Flagellar motors
Ion and nutrient uptake
What are membrane nanowires responsible for
Where are they found
Needed to complete chemical reactions, electrons are transferred along nanowires
Also access insoluble or unavailable metals for energy
Between cells in a biofilm
Do obligate lithotrophs…
Consume organic carbon
Fix carbon dioxide
They consume no organic carbon
They do fix carbon dioxide
What is the name of the specialist electron accepting component of the cell membrane
Oxidoreductase
Electron donors in lithotrophy are often poor, this means they require a … terminal acceptor
Strong
The ammanox reaction accounts for ..% of the nitrogen returned to the atmosphere
50%
Oxidation of sulfir compounds leads to…
Acidification
Why is sulfur oxidation carried out by microbes
Suphur compounds are often abundant and readily available
What happens in sulphurs are oxidised with metal suplhides
Causes hughly acidic mine waste
What effect do suflur-reducing bacteria have on underwater steel bridges
Corrosion
What is bioleaching
Use of lithotrophy to extract metals from uneconomic minerals e.g. Copper mining
Also used for selenium, antinomy, uranium
What is hydrogenotrophy
When hydrogen is used as an electron donor
What environments does hydrogenotrophy occur
Common in soil and can bioremediate pollutants
What is the Faraday constant
The magnitude of electrical charge per mole of electrons
What is the reduction potential
The energy difference between the oxidised and reduced forms of a redox couple (e.g. O2 and H2O)
