L5 Electron Transport Snd Lithotropy Flashcards

1
Q

Before electron transfer, the donor is in a … form

A

Reduced

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2
Q

The donor undegos a … reaction

A

Oxidation

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3
Q

What is meant by a redox couple

A

The oxidised and reduced states of a compound

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4
Q

In organotrophy what is the electron donor and what is the terminal acceptor

A

Organic molecules donate electrons
Oxygen is the terminal acceptor in respiration but there are alternatives (fumarate if anaerobic)

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5
Q

In chemolithotrophy, are electron donors organic or inorganic

A

Inorganic e.g. Fe2+, H2, H2S

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6
Q

What is the terminal electron acceptor in chemolithotrophy

A

Oxygen
There are anaerobic alternatives: NO3- and fumarate

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7
Q

What kind of environments are chemolithotrophs likely to be found in and why

A

Extreme environments as the chemical environment is altered by the chemicals released by microbes

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8
Q

What does Nitrosomonas europaea oxidise

A

Ammonia

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9
Q

Give 2 roles lithotrophy plays in the encironment

A

Weathers bedrock to form soil
Nitrogen and sulfur cycling

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10
Q

∆G of a redox reaction is proportional to…

A

The reduction potential (E) between an electron acceptor and its donor

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11
Q

A positive E means…
Is the ∆G positive or negative

A

Electrons have been gained
Negative - yielding energy

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12
Q

When talking about redox reactions, is it more likely to see millivolts (E) or Gibbs free energy (G)

A

Millivolts (E˚)

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13
Q

What happens if E.coli is present in an environment without oxygen
What happens if oxygen becomes available again

A

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

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14
Q

What is ∆p

A

Proton motive force

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15
Q

How do you calculate proton motive force

A

∆p = ∆v + ∆pH
∆p - proton motive force
∆v - change in charge (in volts)
∆pH - change in pH (concentration of H ions)

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16
Q

How can the proton motive force be used by the cell

A

ATP production
Flagellar motors
Ion and nutrient uptake

17
Q

What are membrane nanowires responsible for
Where are they found

A

Needed to complete chemical reactions, electrons are transferred along nanowires
Also access insoluble or unavailable metals for energy
Between cells in a biofilm

18
Q

Do obligate lithotrophs…
Consume organic carbon
Fix carbon dioxide

A

They consume no organic carbon
They do fix carbon dioxide

19
Q

What is the name of the specialist electron accepting component of the cell membrane

A

Oxidoreductase

20
Q

Electron donors in lithotrophy are often poor, this means they require a … terminal acceptor

21
Q

The ammanox reaction accounts for ..% of the nitrogen returned to the atmosphere

22
Q

Oxidation of sulfir compounds leads to…

A

Acidification

23
Q

Why is sulfur oxidation carried out by microbes

A

Suphur compounds are often abundant and readily available

24
Q

What happens in sulphurs are oxidised with metal suplhides

A

Causes hughly acidic mine waste

25
What effect do suflur-reducing bacteria have on underwater steel bridges
Corrosion
26
What is bioleaching
Use of lithotrophy to extract metals from uneconomic minerals e.g. Copper mining Also used for selenium, antinomy, uranium
27
What is hydrogenotrophy
When hydrogen is used as an electron donor
28
What environments does hydrogenotrophy occur
Common in soil and can bioremediate pollutants
29
What is the Faraday constant
The magnitude of electrical charge per mole of electrons
30
What is the reduction potential
The energy difference between the oxidised and reduced forms of a redox couple (e.g. O2 and H2O)