6 An Introduction to Metabolism

Question 1

The process of cellular respiration, which converts simple sugars such as glucose into CO2 and water, is an example of _____.

Answer 1

a catabolic pathway

Question 2

Which term most precisely describes the cellular process of breaking down large molecules into smaller ones?

Answer 2

catabolism

Question 3

Which of the following is (are) true for anabolic pathways?

Answer 3

They consume energy to build up polymers from monomers.

Question 4

Which of the following is a statement of the first law of thermodynamics?

Answer 4

Energy cannot be created or destroyed.

Question 5

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

Answer 5

entropy of the universe.

Question 6

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

Answer 6

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

Question 7

In general, enzymes are what kinds of molecules?

Answer 7

proteins

Question 8

Enzymes work by _____.

Answer 8

Enzymes work by reducing the energy of activation.

Question 9

Which of the following statements is true concerning catabolic pathways?

Answer 9

They supply energy, primarily in the form of ATP, for the cell’s work.

Question 10

Enzymes are described as catalysts, which means that they _____.

Answer 10

increase the rate of a reaction without being consumed by the reaction

Question 11

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

Answer 11

activation energy.

Question 12

The active site of an enzyme is the region that

Answer 12

is involved in the catalytic reaction of the enzyme.

Question 13

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

Answer 13

by changing the shape of the enzyme’s active site

Question 14

Allosteric enzyme regulation is usually associated with

Answer 14

an enzyme with more than one subunit.

Question 15

Which of the following is an example of cooperativity?

Answer 15

a molecule binding at one unit of a tetramer, allowing faster binding at each of the other three

Question 16

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

Answer 16

feedback inhibition

Question 17

Besides turning enzymes on or off, what other means does a cell use to control enzymatic activity?

Answer 17

localization of enzymes into specific organelles or membranes

Question 18

Which of the following is true of metabolism in its entirety in all organisms?
A) Metabolism depends on a constant supply of energy from food.
B) Metabolism depends on an organism’s adequate hydration.
C) Metabolism uses all of an organism’s resources.
D) Metabolism consists of all the energy transformation reactions in an organism.
E) Metabolism manages the increase of entropy in an organism.

Answer 18

Metabolism consists of all the energy transformation reactions in an organism.

Question 19

Why is ATP an important molecule in metabolism?

Answer 19

It provides energy coupling between exergonic and endergonic reactions.

Question 20

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

Answer 20

The phosphate may be incorporated into any molecule that contains phosphate.

Question 21

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

Answer 21

activation energy

Question 22

Induced Fit

Answer 22

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

Question 23

Zinc, an essential trace element for most organisms, is present in the active site of the enzyme carboxypeptidase. The zinc most likely functions as a(n)

Answer 23

cofactor necessary for enzyme activity.

Question 24

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

Answer 24

by changing the shape of the enzyme’s active site

Question 25

Allosteric enzyme regulation is usually associated with

Answer 25

an enzyme with more than one subunit.