Question 1

Which of the following is true?

Accepted Answer

A)   Enzymes force reactions to proceed in only one direction.
B)   Enzymes alter the equilibrium of the reaction.
C)   Enzymes alter the standard free energy of the reaction.
D)   All of the above.
E)   None of the above.

Question 2

How is free energy useful for understanding enzyme function?

Accepted Answer

Free energy (∆G) is the key thermodynami...

Question 3

The active site of an enzyme:

Accepted Answer

A)   is a series of amino acids which bind the enzyme.
B)   is a linear sequence of amino acids that react with each other.
C)   binds covalently to the substrate.
D)   allows water to enter into the active site and thereby solvate the substrate.
E)   None of the above.

Question 4

A cofactor is best defined as:

Accepted Answer

A)   another protein.
B)   a covalently bound inorganic molecule.
C)   a small molecule that holds the substrate in the active site.
D)   a molecule responsible for most of the catalytic activity of the enzyme.
E)   None of the above E

Question 5

What is the relation between an enzyme-catalyzed reaction and the transition state of a reaction?

Accepted Answer

Enzymes only catalyze reactions that are...

Question 6

How do enzymes facilitate the formation of the transition state?

Accepted Answer

When enzymes bind substrate, free energy...

Question 7

The free energy change (ΔG′) for the oxidation of the sugar molecules in a sheet of paper into CO2 and H2O is large and negative (the = ΔG°′ – 2833 kJ/mol).  Explain why paper is stable at room temperature in the presence of oxygen (O2).

Accepted Answer

Activation energy! While the r...

Question 8

Examples of cofactors include:

Accepted Answer

A)   Zn+2, Mg+2, and Ni+2.
B)   biotin and thiamine pyrophosphate.
C)   pyridoxal phosphate and coenzyme A.
D)   B and C.
E)   A, B, and C.

Question 9

Enzymes accelerate the rate of a chemical reaction by __________________ the free energy of activation of the reaction.

Accepted Answer

The answer of Enzymes accelerate the rate of a chemical...

Question 10

The relationship between ∆G°′ and ∆G is best described as:

Accepted Answer

A)   determined by the temperature.
B)   described by changes in Keq.
C)   differing from standard state to physiological or actual concentrations of reactants and products.
D)   dependent on the reaction mechanism of the reaction.
E)   differing only in terms of the types of reactions used for each value.

Question 11

What are transition-state analogs?

Accepted Answer

These potent inhibitors mimic the struct...

Question 12

If Keq = 1, what is the ∆G°′? If Keq > 1, what is the ∆G°′? If Keq < 1, what is the ∆G°′?

Accepted Answer

∆G°′ = 0; negative value; positive value

Question 13

The difference in values for ∆G and ∆G°′ is in the __________________.

Accepted Answer

concentrat...

Question 14

An enzyme which has been stripped of the small molecules needed for activity is called an __________________.

Accepted Answer

The answer of An enzyme which has been stripped of...

Question 15

You believe a substrate fits into a cleft like a key into a lock, but your roommate does not. Who is right?

Accepted Answer

You are both partially correct. Like a l...

Question 16

How does a rigid, lock-and key-model for substrate binding not fit with the formation of the transition state?

Accepted Answer

The amino acids in the active site must combine with any cofactors and the substrates in an orientation that promotes the active site. This intermediate will not be like the substrate in shape and coordination. Thus, the binding and reaction must allow for a flexible and dynamic binding and active site.

Question 17

What might be the cause of this? Assume the structure of the protein is retained.

Accepted Answer

The dilution and dialysis must have caus...

Question 18

When ΔG for a system is zero, the system is at __________________.

Accepted Answer

The answer of When ΔG for a system is zero,...

Question 19

Choose the correct answer from the list below. Not all of the answers will be used.
-Enzymes that cleave molecules by the addition of water are called ____________.

Accepted Answer

A)  apoenzymes
B)  hydrolyases
C)  active site
D)  transition state
E)  spontaneousF) induced fitG) energyH) prosthetic groupI) lock and keyJ) substrate(s) K) oxidoreductasesL) equilibria

Question 20

For the two reactions (a)  A → B ∆G°′ = 2 kJ mol−1, and (b)  X → Y ∆G°′ = −3.5 kJ mol−1 , which of the following statements is correct?

Accepted Answer

A)   Reaction (a)  is not spontaneous at cellular concentrations.
B)   Reaction (b)  will react very quickly.
C)   Reaction (a)  is a more thermodynamically favorable reaction than is (b) .
D)   Neither reaction is reversible.
E)   None of the above.

Exam 6: Basic Concepts of Enzyme Action

Which of the following is true?

Correct Answer
verified

How is free energy useful for understanding enzyme function?

Correct Answer
verified
Free energy (∆G) is the key thermodynami...
View Answer

The active site of an enzyme:

Correct Answer
verified

A cofactor is best defined as:

Correct Answer
verified
E

What is the relation between an enzyme-catalyzed reaction and the transition state of a reaction?

Correct Answer
verified
Enzymes only catalyze reactions that are...
View Answer

How do enzymes facilitate the formation of the transition state?

Correct Answer
verified
When enzymes bind substrate, free energy...
View Answer

The free energy change (ΔG′) for the oxidation of the sugar molecules in a sheet of paper into CO₂ and H₂O is large and negative (the = ΔG°′ – 2833 kJ/mol). Explain why paper is stable at room temperature in the presence of oxygen (O₂).

Correct Answer
verified
Activation energy! While the r...
View Answer

Examples of cofactors include:

Correct Answer
verified

Enzymes accelerate the rate of a chemical reaction by __________________ the free energy of activation of the reaction.

Correct Answer
verified

The relationship between ∆G°′ and ∆G is best described as:

Correct Answer
verified

What are transition-state analogs?

Correct Answer
verified
These potent inhibitors mimic the struct...
View Answer

If K_eq = 1, what is the ∆G°′? If K_eq > 1, what is the ∆G°′? If K_eq < 1, what is the ∆G°′?

Correct Answer
verified
∆G°′ = 0; negative value; positive value

The difference in values for ∆G and ∆G°′ is in the __________________.

Correct Answer
verified
concentrat...
View Answer

An enzyme which has been stripped of the small molecules needed for activity is called an __________________.

Correct Answer
verified

You believe a substrate fits into a cleft like a key into a lock, but your roommate does not. Who is right?

Correct Answer
verified
You are both partially correct. Like a l...
View Answer

How does a rigid, lock-and key-model for substrate binding not fit with the formation of the transition state?

What might be the cause of this? Assume the structure of the protein is retained.

Correct Answer
verified
The dilution and dialysis must have caus...
View Answer

When ΔG for a system is zero, the system is at __________________.

Correct Answer
verified

Choose the correct answer from the list below. Not all of the answers will be used. -Enzymes that cleave molecules by the addition of water are called ____________.

Correct Answer
verified

For the two reactions (a) A → B ∆G°′ = 2 kJ mol⁻¹, and (b) X → Y ∆G°′ = −3.5 kJ mol⁻¹ , which of the following statements is correct?

Correct Answer
verified

Exam 6: Basic Concepts of Enzyme Action

Which of the following is true?

Correct AnswerverifiedShow Answer

How is free energy useful for understanding enzyme function?

Correct AnswerverifiedFree energy (∆G) is the key thermodynami...View AnswerShow Answer

The active site of an enzyme:

Correct AnswerverifiedShow Answer

A cofactor is best defined as:

Correct AnswerverifiedE

What is the relation between an enzyme-catalyzed reaction and the transition state of a reaction?

Correct AnswerverifiedEnzymes only catalyze reactions that are...View AnswerShow Answer

How do enzymes facilitate the formation of the transition state?

Correct AnswerverifiedWhen enzymes bind substrate, free energy...View AnswerShow Answer

The free energy change (ΔG′) for the oxidation of the sugar molecules in a sheet of paper into CO2 and H2O is large and negative (the = ΔG°′ – 2833 kJ/mol). Explain why paper is stable at room temperature in the presence of oxygen (O2).

Correct AnswerverifiedActivation energy! While the r...View AnswerShow Answer

Examples of cofactors include:

Correct AnswerverifiedShow Answer

Enzymes accelerate the rate of a chemical reaction by __________________ the free energy of activation of the reaction.

Correct AnswerverifiedShow Answer

The relationship between ∆G°′ and ∆G is best described as:

Correct AnswerverifiedShow Answer

What are transition-state analogs?

Correct AnswerverifiedThese potent inhibitors mimic the struct...View AnswerShow Answer

If Keq = 1, what is the ∆G°′? If Keq > 1, what is the ∆G°′? If Keq < 1, what is the ∆G°′?

Correct Answerverified∆G°′ = 0; negative value; positive value

The difference in values for ∆G and ∆G°′ is in the __________________.

Correct Answerverifiedconcentrat...View AnswerShow Answer

An enzyme which has been stripped of the small molecules needed for activity is called an __________________.

Correct AnswerverifiedShow Answer

You believe a substrate fits into a cleft like a key into a lock, but your roommate does not. Who is right?

Correct AnswerverifiedYou are both partially correct. Like a l...View AnswerShow Answer

How does a rigid, lock-and key-model for substrate binding not fit with the formation of the transition state?

What might be the cause of this? Assume the structure of the protein is retained.

Correct AnswerverifiedThe dilution and dialysis must have caus...View AnswerShow Answer

When ΔG for a system is zero, the system is at __________________.

Correct AnswerverifiedShow Answer

Choose the correct answer from the list below. Not all of the answers will be used. -Enzymes that cleave molecules by the addition of water are called ____________.

Correct AnswerverifiedShow Answer

For the two reactions (a) A → B ∆G°′ = 2 kJ mol−1, and (b) X → Y ∆G°′ = −3.5 kJ mol−1 , which of the following statements is correct?

Correct AnswerverifiedShow Answer

Correct Answer
verified

Correct Answer
verified
Free energy (∆G) is the key thermodynami...
View Answer

Correct Answer
verified

Correct Answer
verified
E

Correct Answer
verified
Enzymes only catalyze reactions that are...
View Answer

Correct Answer
verified
When enzymes bind substrate, free energy...
View Answer

The free energy change (ΔG′) for the oxidation of the sugar molecules in a sheet of paper into CO₂ and H₂O is large and negative (the = ΔG°′ – 2833 kJ/mol). Explain why paper is stable at room temperature in the presence of oxygen (O₂).

Correct Answer
verified
Activation energy! While the r...
View Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
These potent inhibitors mimic the struct...
View Answer

If K_eq = 1, what is the ∆G°′? If K_eq > 1, what is the ∆G°′? If K_eq < 1, what is the ∆G°′?

Correct Answer
verified
∆G°′ = 0; negative value; positive value

Correct Answer
verified
concentrat...
View Answer

Correct Answer
verified

Correct Answer
verified
You are both partially correct. Like a l...
View Answer

Correct Answer
verified
The dilution and dialysis must have caus...
View Answer

Correct Answer
verified

Correct Answer
verified

For the two reactions (a) A → B ∆G°′ = 2 kJ mol⁻¹, and (b) X → Y ∆G°′ = −3.5 kJ mol⁻¹ , which of the following statements is correct?

Correct Answer
verified