Question 1

A linear relationship between Vmax and enzyme concentration would be expected when

Accepted Answer

A) [S] m. 
B) [S] >> Km. 
C) [S] = Km. 
D) both [S] m and [S] = Km. 
E) both [S] >> Km and [S] = Km. 
A) [S] m. 
B) [S] >> Km. 
C) [S] = Km. 
D) both [S] m and [S] = Km. 
E) both [S] >> Km and [S] = Km.

Question 2

Feedback inhibition prevents cells from

Accepted Answer

A) the harmful effects of enzyme activation by covalent modification of unneeded enzymes. 
B) making products that are not needed by inhibiting the activity of enzymes in biosynthetic pathways allosterically. 
C) destroying enzymes by proteolytic cleavage when they are needed in biosynthetic pathways. 
D) accumulating unnecessary proteins. 
E) irreversibly inhibiting critical enzymes. 
A) the harmful effects of enzyme activation by covalent modification of unneeded enzymes. 
B) making products that are not needed by inhibiting the activity of enzymes in biosynthetic pathways allosterically. 
C) destroying enzymes by proteolytic cleavage when they are needed in biosynthetic pathways. 
D) accumulating unnecessary proteins. 
E) irreversibly inhibiting critical enzymes.

Question 3

The ________ is the minimum energy required before two molecules can be successful in producing a reaction.

Accepted Answer

The answer of The ________ is the minimum energy required...

Question 4

Ribozymes were discovered ________ protein enzymes,even though they ________.

Accepted Answer

A) before; only catalyze one type of cellular reaction 
B) before; are more heat labile than protein enzymes 
C) after; catalyze many important cellular reactions 
D) after; are the only catalysts found in bacteria and archaea 
E) at the same time as; only catalyze one type of cellular reaction 
A) before; only catalyze one type of cellular reaction 
B) before; are more heat labile than protein enzymes 
C) after; catalyze many important cellular reactions 
D) after; are the only catalysts found in bacteria and archaea 
E) at the same time as; only catalyze one type of cellular reaction

Question 5

Enzyme regulation may occur by several methods.Which of the following is not a means of enzyme regulation?

Accepted Answer

A) substrate-level phosphorylation 
B) feedback inhibition 
C) allosteric regulation 
D) covalent modification 
E) saturation 
A) substrate-level phosphorylation 
B) feedback inhibition 
C) allosteric regulation 
D) covalent modification 
E) saturation

Question 6

As new enzymes are discovered,the EC system for naming enzymes is to be used.The names are to be based on which of the following criteria?

Accepted Answer

A) the name of the substrate 
B) a description of substrate function 
C) an indication of the size of the substrate 
D) the six major classes of enzyme function 
E) the size of the enzyme 
A) the name of the substrate 
B) a description of substrate function 
C) an indication of the size of the substrate 
D) the six major classes of enzyme function 
E) the size of the enzyme

Question 7

________ are a class of enzymes responsible for the movement of functional groups from one molecule to another.

Accepted Answer

The answer of ________ are a class of enzymes responsible...

Question 8

The enzyme carbonic anhydrase catalyzes the formation of carbonic acid from carbon dioxide and water.Imagine that you have two sealed tubes with carbon dioxide gas above a buffer containing water and carbon dioxide.One tube has carbonic anhydrase and the other does not.After 24 hours,both tubes are at equilibrium.Which statement below accurately describes the conditions in the tubes?

Accepted Answer

A) The tube with carbonic anhydrase will have a lower concentration of carbon dioxide and a higher concentration of carbonic acid than the tube with any enzyme. 
B) The tube with carbonic anhydrase will have a higher concentration of carbon dioxide and a lower concentration of carbonic acid than the tube with any enzyme. 
C) The tubes will have equal concentrations of carbon dioxide and carbonic acid. 
D) The tube with carbonic anhydrase will have a higher concentration of carbonic acid than the tube with any enzyme,but the concentration of carbon dioxide will be the same in both tubes. 
E) It is not possible to determine the relative concentrations of the products and reactants without more information about carbonic anhydrase,such as the Km. 
A) The tube with carbonic anhydrase will have a lower concentration of carbon dioxide and a higher concentration of carbonic acid than the tube with any enzyme. 
B) The tube with carbonic anhydrase will have a higher concentration of carbon dioxide and a lower concentration of carbonic acid than the tube with any enzyme. 
C) The tubes will have equal concentrations of carbon dioxide and carbonic acid. 
D) The tube with carbonic anhydrase will have a higher concentration of carbonic acid than the tube with any enzyme,but the concentration of carbon dioxide will be the same in both tubes. 
E) It is not possible to determine the relative concentrations of the products and reactants without more information about carbonic anhydrase,such as the Km.

Question 9

Which of the following is an enzyme?

Accepted Answer

A) iron 
B) histidine 
C) carboxypeptidase A 
D) ATP 
E) N-acetylmuramic acid 
A) iron 
B) histidine 
C) carboxypeptidase A 
D) ATP 
E) N-acetylmuramic acid

Question 10

A competitive inhibitor

Accepted Answer

A) binds at a site other than the active site. 
B) irreversibly binds and inactivates the enzyme. 
C) cannot be processed by the enzyme. 
D) does not inhibit enzyme activity but does lower substrate concentration. 
E) binds to and inactivates the substrate. 
A) binds at a site other than the active site. 
B) irreversibly binds and inactivates the enzyme. 
C) cannot be processed by the enzyme. 
D) does not inhibit enzyme activity but does lower substrate concentration. 
E) binds to and inactivates the substrate.

Question 11

An enzyme

Accepted Answer

A) decreases the rate of a reaction. 
B) binds substrates in a manner that facilitates the formation of product. 
C) changes the position of the equilibrium of the reaction. 
D) does not change the rate at which the equilibrium is achieved. 
E) is always a protein. 
A) decreases the rate of a reaction. 
B) binds substrates in a manner that facilitates the formation of product. 
C) changes the position of the equilibrium of the reaction. 
D) does not change the rate at which the equilibrium is achieved. 
E) is always a protein.

Question 12

Covalent modification

Accepted Answer

A) can activate an enzyme. 
B) affects the activity of an enzyme by adding or removing a chemical group. 
C) can involve the addition of phosphate groups. 
D) produces modifications that can sometimes be reversed. 
E) All of these are correct. 
A) can activate an enzyme. 
B) affects the activity of an enzyme by adding or removing a chemical group. 
C) can involve the addition of phosphate groups. 
D) produces modifications that can sometimes be reversed. 
E) All of these are correct.

Question 13

All of the following are examples of ribozymes or ribozyme activity except

Accepted Answer

A) peptidyl transferase activity. 
B) autocatalytic RNAs. 
C) ribonuclease P. 
D) intron removal from pre-rRNA. 
E) zymogen. 
A) peptidyl transferase activity. 
B) autocatalytic RNAs. 
C) ribonuclease P. 
D) intron removal from pre-rRNA. 
E) zymogen.

Question 14

The equation A − PO4 + B → A + B − PO4 would be catalyzed by which of the following classes of enzymes?

Accepted Answer

A) transferases 
B) oxidoreductases 
C) hydrolases 
D) ligases 
E) isomerases 
A) transferases 
B) oxidoreductases 
C) hydrolases 
D) ligases 
E) isomerases

Question 15

An enzyme is active in the stomach of an animal but quickly loses its activity when it leaves the stomach.This example illustrates that enzymes are

Accepted Answer

A) specific to the organs in which they are produced. 
B) inactivated by movement. 
C) sensitive to changes in pH. 
D) digested in the small intestine. 
E) consumed by the quantities of substrate in the small intestine. 
A) specific to the organs in which they are produced. 
B) inactivated by movement. 
C) sensitive to changes in pH. 
D) digested in the small intestine. 
E) consumed by the quantities of substrate in the small intestine.

Question 16

The induced-fit model

Accepted Answer

A) was proposed by Hans Buchner. 
B) distorts the shape of the enzyme and the substrate. 
C) is also called the lock-and-key model. 
D) states that enzyme-substrate interactions are rigid. 
E) proposes that very strong covalent bonds are formed upon substrate binding. 
A) was proposed by Hans Buchner. 
B) distorts the shape of the enzyme and the substrate. 
C) is also called the lock-and-key model. 
D) states that enzyme-substrate interactions are rigid. 
E) proposes that very strong covalent bonds are formed upon substrate binding.

Question 17

Azidothymidine (AZT)is a(n)________ used in the treatment of AIDS and targets the enzyme reverse transcriptase.

Accepted Answer

The answer of Azidothymidine (AZT)is a(n)________ used in the treatment...

Question 18

Which of the following is/are means whereby a catalyst can lower the activation energy of a reaction?

Accepted Answer

A) decreasing the number of reactive molecules 
B) altering the temperature within the cell to one appropriate for reactions to proceed 
C) quantum tunneling 
D) inefficient collisions 
E) permanently binding substrates 
A) decreasing the number of reactive molecules 
B) altering the temperature within the cell to one appropriate for reactions to proceed 
C) quantum tunneling 
D) inefficient collisions 
E) permanently binding substrates

Question 19

Which of the following variables is not part of the Michaelis-Menten equation?

Accepted Answer

A) kcat 
B) Km 
C) Vmax 
D) [S] 
E) v 
A) kcat 
B) Km 
C) Vmax 
D) [S] 
E) v

Question 20

The site on an enzyme that will bind the substrate is called the

Accepted Answer

A) prosthetic group. 
B) catalyst. 
C) active site. 
D) metastable site. 
E) activation site. 
A) prosthetic group. 
B) catalyst. 
C) active site. 
D) metastable site. 
E) activation site.

Exam 6: Enzymes: the Catalysts of Life

A linear relationship between Vmax and enzyme concentration would be expected when

Feedback inhibition prevents cells from

The ________ is the minimum energy required before two molecules can be successful in producing a reaction.

Ribozymes were discovered ________ protein enzymes,even though they ________.

Enzyme regulation may occur by several methods.Which of the following is not a means of enzyme regulation?

As new enzymes are discovered,the EC system for naming enzymes is to be used.The names are to be based on which of the following criteria?

________ are a class of enzymes responsible for the movement of functional groups from one molecule to another.

Which of the following is an enzyme?

A competitive inhibitor

An enzyme

Covalent modification

All of the following are examples of ribozymes or ribozyme activity except

The equation A − PO4 + B → A + B − PO4 would be catalyzed by which of the following classes of enzymes?

An enzyme is active in the stomach of an animal but quickly loses its activity when it leaves the stomach.This example illustrates that enzymes are

The induced-fit model

Azidothymidine (AZT)is a(n)________ used in the treatment of AIDS and targets the enzyme reverse transcriptase.

Which of the following is/are means whereby a catalyst can lower the activation energy of a reaction?

Which of the following variables is not part of the Michaelis-Menten equation?

The site on an enzyme that will bind the substrate is called the

A Preview of Cell Biology

The Chemistry of the Cell

The Macromolecules of the Cell

Cells and Organelles

Bioenergetics: the Flow of Energy in the Cell

Membranes: Their Structure,function,and Chemistry

Transport Across Membranes: Overcoming the Permeability Barrier

Chemotrophic Energy Metabolism: Glycolysis and Fermentation

Chemotrophic Energy Metabolism: Aerobic Respiration

Phototrophic Energy Metabolism: Photosynthesis

The Endomembrane System

Cytoskeletal Systems

Cellular Movement: Motility and Contractility

Beyond the Cell: Cell Adhesions, cell Junctions, and Extracellular Structures

The Structural Basis of Cellular Information: Dna, chromosomes, and the Nucleus

DNA Replication, repair, and Recombination

Gene Expression: Ithe Genetic Code and Transcription

Gene Expression: Iiprotein Synthesis and Sorting

The Regulation of Gene Expression

Molecular Biology Techniques for Cell Biology

Signal Transduction Mechanisms: Ielectrical and Synaptic Signaling in Neurons

Signal Transduction Mechanisms: Iimessengers and Receptors

The Cell Cycle and Mitosis

Sexual Reproduction,meiosis,and Genetic Recombination

Filters

A linear relationship between V_max and enzyme concentration would be expected when

Ribozymes were discovered protein enzymes,even though they .

The equation A − PO₄ + B → A + B − PO₄ would be catalyzed by which of the following classes of enzymes?