Dec 9, 2010
20
0
Status
Dental Student
The standard free energy change for a metabolic pathway:

A. is positive for spontaneous pathways.
B. is inversely proportional to the rate of the overall pathway.
C. is lower in the presence of the pathway enzymes.
D. is the sum of all the individual standard free energy values.
E. depends on the free energy of the rate limiting reaction.

:confused::confused:

 
May 10, 2012
880
9
Middle West
Status
MD/PhD Student
The standard free energy change for a metabolic pathway:

A. is positive for spontaneous pathways.
B. is inversely proportional to the rate of the overall pathway.
C. is lower in the presence of the pathway enzymes.
D. is the sum of all the individual standard free energy values.
E. depends on the free energy of the rate limiting reaction.

:confused::confused:

d=delta
Standard free energy is dG=dH-T*dS.

A. Wrong. dG is negative for spontaneous reactions.
B. Wrong. dG doesn't tell us anything about rate.
C. Wrong. Enzymes don't change dG, they just lower Ea.
D. YES. Take the simplest example of a series of two reactions: A->B->C. Let's say the dG for A->B is 100kJ/mol and B->C is -200kJ/mol. If you have 1 mol of A and convert it all to C, what would the overall change in energy? Makes sense that it would be -100kJ wouldn't it?
E. No. Overall rate generally depends on the rate limiting reaction, not free energy change.