Chapter 6, Metabolism
Which of the following represents the activation energy needed for the enzyme-catalyzed reverse reaction, C+D->A+B, in Figure X?
A
How does a non competitive inhibitor decrease the rate of an enzyme reaction?
By changing the shape of the enzyme's active site
Which of the following represents the activation energy needed for the non catalyze reverse reaction, C+D->A+B, in Figure X?
E
Which of the following is a statement of the first law of thermodynamics?
Energy cannot be created or destroyed
Whenever energy is transformed, there is always an increase in the
Entropy of the universe
All of the biochemical pathways in a cell constitute
Metabolism
Which of the following is the smallest closed system?
The Universe
Which of the following statements is true about enzyme-catalyzed reactions?
The reaction is faster than the same reaction in the absence of the enzyme
Which of the following is true for all exergonic reactions?
The reaction proceeds with a net release of free energy.
Which of the following is (are) true for anabolic pathways?
They consume energy to build up polymers from monomers
An important group of peripheral membrane proteins are enzymes such as phospholipases that cleave the head groups of phospholipids. What properties must these enzymes exhibit?
Water solubility
The mechanism in which the end product of a metabolic pathway inhibits an earlier step in the pathway is most precisely described as
Feedback inhibition
According to the induced fit hypothesis of enzyme catalysis, which of the following is correct?
The binding of the substrate changes the shape of the enzyme's active site
When ATP releases some energy, it also releases inorganic phosphate. What purpose does this serve (if any) in the cell?
The phosphate may be incorporated into any molecule that contains phosphate
The mathematical expression for the change in free energy of a system is A (triangle)G=A (triangle) H-TA (triangle) S. Which of the following is (are) correct?
A (triangle) is the change in free energy.
Which of the following is an example of potential rather than kinetic energy?
A molecule of glucose
Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the reaction's
Activation energy
Allosteric enzyme regulation is usually associated with
An enzyme with more than one subunit
Which of the following types of reactions would decrease the entropy within a cell?
Anabolic reactions
Which of the following represents the activation energy required for a enzyme-catalyzed reaction in Figure X?
B
Which of the following terms best describes the forward reaction in Figure X?
Exergonic, A (triangle)G<0
Which of the following represents the activation energy required for a non-catalyzed reaction in Figure X?
C
Endergonic reactions
Can only occur if there is an input of energy
Which term most precisely describes the cellular process of breaking down large molecules into smaller ones?
Catabolism
When you have a severe fever, what grave consequence may occur if the fever is not controlled?
Change in the tertiary structure of your enzymes
Increasing the substrate concentration in an enzymatic reaction could overcome which of the following?
Competitive inhibition
Which of the following in Figure 8.1 would be the same in either an enzyme-catalyze or non-catalyzed reaction?
D
Which of the following represents the A (triangle)G of the reaction in Figure X?
D
Which of the following represents the difference between the free-energy content of the reaction and the free-energy content of the products in Figure X?
D
Which of the following is true of enzymes?
Enzymes increase the rate of chemical reaction by lowering activation energy barriers
Which of the following statements regarding enzymes is true?
Enzymes increase the rate of reaction by making the reaction more exergonic
Which of the following statements is a logical consequence of the second law of thermodynamics?
Every chemical reaction must increase the total entropy of the universe
Some of the drugs used to treat HIV patients are competitive inhibitors of the HIV reverse transcriptase enzyme. Unfortunately, the high mutation rate of HIV means that the virus rapidly acquires mutations with amino acid changes that make them resistant to these competitive inhibitors. Where in the reverse transcriptase enzyme would such amino acid changes most likely occur in drug-resistant viruses?
In or near the active site
The active site of an enzyme is the region that
Is involved in the catalytic reaction of the enzyme
Why is ATP an important molecule in metabolism?
It provides energy coupling between exergonic and endergonic reactions
Which statement(s) describe the currently accepted theory of how an enzyme and it substrate fit together?
b) The substrate is like a key that fits into the enzyme, which is like a lock d) As the substrate binds to the enzyme, the shape of the active site changes to accommodate the reaction
