II.
Compare DG0' and DG
Compare a highly-spontaneous reaction to a reaction near-equilibrium
Summary of Bioenergetics:
1. DG is independent of the reaction pathway and gives no information about the reaction rates.
2. The sign (neg or pos) of DG denotes the direction of the reaction. The number is the magnitude.
3. When DG << 0, the reaction is spontaneous, and will proceed in the direction written.
4. When DG = 0, the reaction is at equilibrium. No net reaction in either direction.
5. When DG is close to equilibrium, the reaction becomes dependent on the relative concentrations of product and reactant. Since DG is a function of [product]/[reactant], DG will change when the relative concentrations of product and reactant change.
6. The DG of coupled reactions are additive.
Regulation of enzyme-catalyzed reactions
(p78, #15)
Indicate whether each of the following enzyme-catalyzed reactions would be more likely to be regulated (R) or unregulated (U).
a) DG close to zero
b) last step before a branch point
c) highly spontaneous
d) first step after a branch point
e) maximum catalysis required at all times
f) same reaction used in pathway making B from A and in pathway breaking down B to A
III.
History and overview
For each reaction: DG0' and DG, enzyme class, regulation
IV.
Glycolysis and gluconeogenesis are opposing pathways. Assign letters to the intermediates/substrates and numbers to the enzymes in each metabolic pathway. Draw out pathway with proper arrow notation and highlight the regulated steps.
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