Chapter 13. Bioenergetics and Biochemical Reaction Types

Question 1

Know how to identify biological oxidations and reductions

Answer 1

One species donates electrons (oxidized)

One species accepts electrons (reduced)

Question 2

Know how to calculate ΔG’o when combining reactions or how to calculate K’eq from ΔG’o or ΔG from ΔG’o and the real time mass ratio (mass quotient, Q). (2)

Answer 2

Given A + B C + D

deltaG = deltaG’o + RT ln [C][D]/[A][B], not usually at equilibrium

Question 3

What important information does deltaG = 0 give?

Answer 3

The equation is at equilibrium, so deltaG’o = -RT ln[C][D]/[A][B] = -RT ln K’eq

Question 4

What does each piece represent? ΔG = - nF deltaE, ΔG’o = - nF deltaE’o

Answer 4

F is the Faraday constant, n is the number of electrons transferred
• By convention E’o of the electron receptor (reductant) minus E’o of the electron donor (oxidant) equals ΔE’o
• E(half reaction red) = E’o + RT/nF ln [e- acceptor]/[e- donor]
• E(half reaction ox) = E’o + RT/nF ln [e- donor]/[e- acceptor]
• Then calculate dE = E(half reaction red) - E(half reaction ox)
Then using the first equation, one can calculate ΔG

Question 5

Know why ATP hydrolysis is a high energy process

Answer 5

ATP provides energy not by the breaking of the bond holding the final Pi but by 3 other molecular events

• Relief of charge repulsion between oxygens on the phosphates
• Resonance stabilization of the inorganic phosphate released
• Ionization of ADP2- to ADP3-