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Take-home 2. Use the redox potential table ("electron tower") provided to answer the following questions.
Redox compound E(mV) 2-A. Of the following redox couples, circle the one that would represent the best electron donor (molecule on the right side of the slash)? (1 pt)
a) CO2/formate 432
b) SO2/HSO3 414
c) SO/HSO4- 402
d) NO2-/NO3- -371
e) Fe3+/Fe2+ -398
f) NAD+/NADH 320
g) Cytochrome c ox/red 290
2-B. Of the following redox couples, circle the one that would represent the best electron acceptor (molecule on the left side of the slash)? (1 pt)
a) S/HS- 270
b) SO2/HSO3 244
c) NO2-/NO3- -190
d) Fe3+/Fe2+ -190
e) N2O/N2 -190
f) FMN/FMNH2 -173
2-C. You have isolated an anaerobic organism that is capable of using H2 as an electron donor and either S (elemental sulfur, reduced to HS-) or Fe3+ (reduced to Fe2+) as electron acceptors. When grown in the presence of H2, Fe3+, and S, would you expect the organism to preferentially use Fe3+ or S, or would it have no preference? Why? (2 pts)
2-D. Demethylvitamin K,ox/red +25
SO3/SO4- +33
Ubiquinone ox/red +113
SO2-/SO3- +225
NO2-/NO3- +350
NO2/NO +433
Fe2+/Fe3+ +772
O2/H2O +818
NO/N2O +1175
NO/N2 +1355
