Enzymes

1. In the formula deltaG = deltaH - deltaS * T

a. What does the change in free energy depend upon?

b. Under what condition would a reaction occur spontaneously?

c. Why is it true that total free energy in a reaction system cannot be accurately measured, but

the change in free energy can be?

d. Devise and explain is one method for measuring change in free energy.

e. Are spontaneous reactions also instantaneous? Explain.

f. Are reactions with a negative êG exergonic or endergonic?

g. Describe the state of a reaction in dynamic equilibrium.

h. How do cells drive endergonic reactions?

2. Describe the structure of ATP. What is significant about the bond between the second and third

phosphate group.

3. Using the reaction that synthesizes the amino acid glutamine from glutamate and ammonia,

explain energy coupling . How much net free energy is derived from this set of reactions?

4. Fully describe all the characteristics of enzymes, incluting the factors that affect rates catalyzed by

enzymes. This is not a short answer question!

5. Draw a graph that shows the change in free energy as a non-catalyzed reaction proceeds. Then

draw a second line on the same graph that shows the same reaction to which has been added an

appropriate enzyme.

6. Describe the relationship that exists between the concentration of a substrate and the rate (Vo) of a

reaction assisted by an enzyme.

7. Describe, with an appropriate diagram, an allosteric interaction.

8. What is the difference between competitive and noncompetitive inhibition?