Metabolism

Question 1

What is potential energy?

Answer 1

Potential energy is the energy posessed by an object or person but isn’t currently being utilized.

Question 2

What is kinetic energy?

Answer 2

The amount of kinetic energy an object has is due to movement. Water flowing down a cliff has kinetic energy.

Question 3

What is activation energy?

Answer 3

Activation energy is the energy required for a reaction to occur and is at it’s lower when the reaction is catalyzed.

Question 4

What is an exergonic reaction?

Answer 4

A exergonic reaction proceeds with a net release of energy and is spontaneous.

Question 5

What is an endergonic reaction?

Answer 5

An endergonic reaction absorbs free energy from its surroundings and is nonspontaneous

Question 6

What is entropy?

Answer 6

Entropy is a measure of disorder in a system.

Gases have higher entropy the liquids and liquids have higher entropy then solids.

Question 7

What is ATP?

Answer 7

ATP is the primary currency of energy for the cell.

It has an adenosine backbone with three phosphate groups attached.

Question 8

Which of the following is true is (are) true for anabolic pathways?
A)They do not depend on enzymes.
B) They are unusually high spontaneous chemical reactions
C) They consume energy to build up polymers from monomers.
D)They release energy as they degrade polymers to monomers.
E)They consume energy to decrease the entropy of the organism and it’s enviroment

Answer 8

A) They do not depend on enzymes.

Question 9

Whenever energy is transformed, there is always an increase in the:

Answer 9

entropy of the universe.

Question 10

Which of the following statements is a logical consequence of the second law of thermodynamics?

Answer 10

Every chemical reaction must increase the total entropy of the universe.

Question 11

Which reaction would decrease the entropy within a cell?

Answer 11

Anabolic reactions

Question 12

Which of the following is an example of potential rather than kinetic energy?
A) the muscle contractions of a person mowing grass
B) water rushing over Niagara Falls
C) light flashes emitted by a firefly
D) a molecule of glucose
E) the flight of an insect foraging for food

Answer 12

D) A molecule of glucose

Question 13

Which of the following is the smallest closed system?
A) a cell
B) an organism
C) an ecosystem
D) Earth
E) the universe

Answer 13

E) The universe

Question 14

The mathematical expression for the change in free energy of a system is ΔG =ΔH - TΔS. Which of the following is (are) correct?
A) ΔS is the change in enthalpy, a measure of randomness.
B) ΔH is the change in entropy, the energy available to do work.
C) ΔG is the change in free energy.
D) T is the temperature in degrees Celsius.

Answer 14

C) ΔG is the change in free energy.

Question 15

Which of the following is true for all exergonic reactions?
A) The products have more total energy than the reactants.
B) The reaction proceeds with a net release of free energy.
C) The reaction goes only in a forward direction: all reactants will be converted to products, but no products will be converted to reactants.
D) A net input of energy from the surroundings is required for the reactions to proceed.
E) The reactions are rapid.

Answer 15

B) The reaction proceeds with a net release of free energy.

Question 16

Why is ATP an important molecule in metabolism?

Answer 16

It provides energy coupling between exergonic and endergonic reactions.

Question 17

When ATP releases some energy, it also releases inorganic phosphate. What purpose does this serve (if any) in the cell?

Answer 17

The phosphate may be incorporated into any molecule that contains phosphate

Question 18

Which of the following statements is true about enzyme-catalyzed reactions?
A) The reaction is faster than the same reaction in the absence of the enzyme.
B) The free energy change of the reaction is opposite from the reaction that occurs in the absence of the enzyme.
C) The reaction always goes in the direction toward chemical equilibrium.
D) Enzyme-catalyzed reactions require energy to activate the enzyme.
E) Enzyme-catalyzed reactions release more free energy than noncatalyzed reactions.

Answer 18

The reaction is faster than the same reaction in the absence of the enzyme.

Question 19

Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the
reaction’s

Answer 19

activation energy.

Question 20

Which of the following statements regarding enzymes is true?
A) Enzymes increase the rate of a reaction by making the reaction more exergonic.
B) Enzymes increase the rate of a reaction by lowering the activation energy barrier.
C) Enzymes increase the rate of a reaction by reducing the rate of reverse reactions.
D) Enzymes change the equilibrium point of the reactions they catalyze.
E) Enzymes make the rate of a reaction independent of substrate concentrations.

Answer 20

B) Enzymes increase the rate of a reaction by lowering the activation energy barrier.

Question 21

The active site of an enzyme is the region that

Answer 21

is involved in the catalytic reaction of the enzyme.

Question 22

According to the induced fit hypothesis of enzyme catalysis, which of the following is correct?
A) The binding of the substrate depends on the shape of the active site.
B) Some enzymes change their structure when activators bind to the enzyme.
C) A competitive inhibitor can outcompete the substrate for the active site.
D) The binding of the substrate changes the shape of the enzyme’s active site.
E) The active site creates a microenvironment ideal for the reaction.

Answer 22

D) The binding of the substrate changes the shape of the enzyme’s active site.

Question 23

Increasing the substrate concentration in an enzymatic reaction could overcome which of the following?
A) denaturization of the enzyme
B) allosteric inhibition
C) competitive inhibition
D) saturation of the enzyme activity
E) insufficient cofactors

Answer 23

C) competitive inhibition

Question 24

19) Which of the following is true of enzymes?
A) Nonprotein cofactors alter the substrate specificity of enzymes.
B) Enzyme function is increased if the 3-D structure or conformation of an enzyme is altered.
C) Enzyme function is independent of physical and chemical environmental factors such as pH and temperature.
D) Enzymes increase the rate of chemical reaction by lowering activation energy barriers.
E) Enzymes increase the rate of chemical reaction by providing activation energy to the substrate.

Answer 24

D) Enzymes increase the rate of chemical reaction by lowering activation energy barriers.

Question 25

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?

Answer 25

In or near the active site.

Question 26

When you have a severe fever, what grave consequence may occur if the fever is not controlled?

Answer 26

change in the tertiary structure of your enzymes

Question 27

How does a noncompetitive inhibitor decrease the rate of an enzyme reaction?

Answer 27

by changing the shape of the enzyme’s active site

Question 28

The mechanism in which the end product of a metabolic pathway inhibits an earlier step in the pathway is most precisely described as

Answer 28

feedback inhibition.

Question 29

Allosteric enzyme regulation is usually associated with

Answer 29

an enzyme with more than one subunit

Question 30

5) An important group of peripheral membrane proteins are enzymes such as the phospholipases that cleave the head groups of
phospholipids. What properties must these enzymes exhibit?

Answer 30

Water solubility

Question 31

All of the biochemical pathways in a cell constitute:

Answer 31

Metabolism.

Question 32

Endergonic reactions:

Answer 32

Can only occur if there is an input of energy.

Question 33

Which statement(s) describe the currently accepted theory of how an enzyme and it substrate fit together?A) as the product is released, the enzyme breaks down
B) the substrate is like a key that fits into the enzyme, which is like a lock
C) the active site is permanently changed by its interactions with the substrate
D) as the substrate binds to the enzyme, the shape of the active site changes to accommodate the reaction
E) both B and D

Answer 33

E) Both B & D.