BIO 311C
Introductory Biology I
K. Sathasivan
In Class Activity 8.2 Metabolism – ATP, Energy Coupling and Enzymes
Name ____________________________ Discussion: ____________
A. Multiple Choice Questions
1) Which of the following statements regarding enzymes is true?
A) Enzymes decrease the rate of a reaction.
B) Enzymes maintain substrate concentrations.
C) Enzymes are used up in the reactions they catalyze.
D) Enzymes increase the activation energy and then decrease it.
E) Enzymes lower the activation energy and releases free energy.
2) What happens when a suitable substrate binds to an enzyme?
A) substrate binding with the enzyme results in ATP hydrolysis.
B) the active site amino acids bond with the substrate.
C) substrate binds with cofactors first and then to the enzyme.
D) enzyme immediately breaks the substrate and releases the products.
E) substrate binds to regulatory site of the enzyme
3) Chemical equilibrium
A) is a dynamic state.
B) represents a state of negative energy change.
C) represents a state of positive energy change.
D) cannot exist in nature.
G = 0.
4) If the enzyme phosphohexosisomerase is added to a 0.3 M solution of fructose 6-phosphate,
and the reaction is allowed to proceed to equilibrium, the final concentrations are 0.2 M
glucose 6-phosphate and 0.1 M fructose 6-phosphate. These data give an equilibrium
constant of 2. What is the equilibrium constant if the initial concentration of fructose 6phosphate is 3 M?
A) 2
B) 3
C) 5
D) 10
E) 20
5) If an enzyme reaction is started with 100 mM Dihydroxyacetone phosphate and at equilibrium
the product Glyceraldehyde 3-Phosphate formed was 80 mM. What is the Km of this enzyme
reaction?
A) 12.5
B) 0.8
C) 80 %
D) 4
E) 8
6) ATP Hydrolysis yields 7.3 Kcal/mol free energy and it is coupled with many enzyme reactions
that would not otherwise happen. Which of the following reaction can be coupled with ATP
hydrolysis to become a favorable or spontaneous reaction. A reaction with a ΔG value of
_______ Kcal/mol.
A) -5.8
B) -7.3
C) 10.5
D) 5.3
E) 0
B. Short Answer Application Questions
1. Develop a hypothesis as to why cells have evolved to use ATP as their main energy
source. How will you test this hypothesis?
2. Compare and contrast simple Vs Allosteric enzymes. List three common and three
different features among them.
3. List five metabolic processes or reactions in the human body that would not otherwise
happen without the input of ATP hydrolysis.