Question 1

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 
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 2

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 3

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 4

How do enzymes facilitate the formation of the transition state?

Accepted Answer

When enzymes bind substrate, free energy

Question 5

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 6

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. 
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 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

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) spontaneous
F)induced fit
G)energy
H)prosthetic group
I)lock and key
J)substrate(s)
K)oxidoreductases
L)equilibria 
A) apoenzymes 
B) hydrolyases 
C) active site 
D) transition state 
E) spontaneous
F)induced fit
G)energy
H)prosthetic group
I)lock and key
J)substrate(s)
K)oxidoreductases
L)equilibria

Question 9

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. 
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.

Question 10

How is free energy useful for understanding enzyme function?

Accepted Answer

Free energy (∆G) is the key thermodynami

Question 11

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

Accepted Answer

concentrat

Question 12

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 13

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 14

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

Accepted Answer

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

Question 15

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. 
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 16

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 17

What are transition-state analogs?

Accepted Answer

These potent inhibitors mimic the struct

Question 18

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. 
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 19

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. 
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 20

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

Accepted Answer

Enzymes only catalyze reactions that are

Exam 6: Basic Concepts of Enzyme Action

A cofactor is best defined as:

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

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

How do enzymes facilitate the formation of the transition state?

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

Examples of cofactors include:

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).

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 ____________.

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?

How is free energy useful for understanding enzyme function?

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

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

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

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

Which of the following is true?

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

What are transition-state analogs?

The active site of an enzyme:

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

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

Biochemistry and the Unity of Life

Water, Weak Bonds, and the Generation of Order Out of Chaos

Amino Acids

Protein Three-Dimensional Structure

Techniques in Protein Biochemistry

Kinetics and Regulation

Mechanisms and Inhibitors

Hemoglobin: an Allosteric Protein

Carbohydrates

Lipids

Membrane Structure and Function

Signal Transduction Pathways

Digestion: Turning a Meal Into Cellular Biochemicals

Metabolism: Basic Concepts and Design

Glycolysis

Gluconeogenesis

Preparation for the Cycle

Harvesting Electrons From the Cycle

The Electron Transport Chain

The Proton-Motive Force

The Light Reactions

The Calvin Cycle

Glycogen Degradation

Glycogen Synthesis

The Pentose Phosphate Pathway

Fatty Acid Degredation

Fatty Acid Synthesis

Lipid Synthesis

Amino Acid Degradation and the Urea Cycle

Amino Acids Synthesis

Nucleotide Metabolism

The Structure of Informational Macromolecules: Dna and Rna

DNA Replication

DNA Repair and Recombination

RNA Synthesis and Regulation in Prokaryotes

Gene Expression in Eukaryotes

RNA Processing in Eukaryotes

The Genetic Code

The Mechanism of Protein Synthesis

Recombinant DNA Techniques

Filters

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

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).

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?