L5 Electron Transport Snd Lithotropy

Question 1

Before electron transfer, the donor is in a … form

Answer 1

Reduced

Question 2

The donor undegos a … reaction

Answer 2

Oxidation

Question 3

What is meant by a redox couple

Answer 3

The oxidised and reduced states of a compound

Question 4

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

Answer 4

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

Question 5

In chemolithotrophy, are electron donors organic or inorganic

Answer 5

Inorganic e.g. Fe2+, H2, H2S

Question 6

What is the terminal electron acceptor in chemolithotrophy

Answer 6

Oxygen
There are anaerobic alternatives: NO3- and fumarate

Question 7

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

Answer 7

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

Question 8

What does Nitrosomonas europaea oxidise

Answer 8

Ammonia

Question 9

Give 2 roles lithotrophy plays in the encironment

Answer 9

Weathers bedrock to form soil
Nitrogen and sulfur cycling

Question 10

∆G of a redox reaction is proportional to…

Answer 10

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

Question 11

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

Answer 11

Electrons have been gained
Negative - yielding energy

Question 12

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

Answer 12

Millivolts (E˚)

Question 13

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

Answer 13

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

Question 14

What is ∆p

Answer 14

Proton motive force

Question 15

How do you calculate proton motive force

Answer 15

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

Question 16

How can the proton motive force be used by the cell

Answer 16

ATP production
Flagellar motors
Ion and nutrient uptake

Question 17

What are membrane nanowires responsible for
Where are they found

Answer 17

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

Question 18

Do obligate lithotrophs…
Consume organic carbon
Fix carbon dioxide

Answer 18

They consume no organic carbon
They do fix carbon dioxide

Question 19

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

Answer 19

Oxidoreductase

Question 20

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

Answer 20

Strong

Question 21

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

Answer 21

50%

Question 22

Oxidation of sulfir compounds leads to…

Answer 22

Acidification

Question 23

Why is sulfur oxidation carried out by microbes

Answer 23

Suphur compounds are often abundant and readily available

Question 24

What happens in sulphurs are oxidised with metal suplhides

Answer 24

Causes hughly acidic mine waste

Question 25

What effect do suflur-reducing bacteria have on underwater steel bridges

Answer 25

Corrosion

Question 26

What is bioleaching

Answer 26

Use of lithotrophy to extract metals from uneconomic minerals e.g. Copper mining
Also used for selenium, antinomy, uranium

Question 27

What is hydrogenotrophy

Answer 27

When hydrogen is used as an electron donor

Question 28

What environments does hydrogenotrophy occur

Answer 28

Common in soil and can bioremediate pollutants

Question 29

What is the Faraday constant

Answer 29

The magnitude of electrical charge per mole of electrons

Question 30

What is the reduction potential

Answer 30

The energy difference between the oxidised and reduced forms of a redox couple (e.g. O2 and H2O)