Question 1

Describe the reaction coordinate diagram for a specific-acid-catalyzed reaction.

Accepted Answer

A) one peak 
B) two peaks, second peak is larger 
C) two peaks, second peak is smaller 
D) two peaks, equal size 
E) three peaks, middle peak is larger 
A) one peak 
B) two peaks, second peak is larger 
C) two peaks, second peak is smaller 
D) two peaks, equal size 
E) three peaks, middle peak is larger

Question 2

Which of the following residues acts as a general-acid catalyst in aldolase but as a general-base catalyst in chymotrypsin?

Accepted Answer

A) methionine 
B) histidine 
C) cysteine 
D) asparagine 
E) lysine 
A) methionine 
B) histidine 
C) cysteine 
D) asparagine 
E) lysine

Question 3

The reaction below occurs by a general-acid catalyzed mechanism. Use curved arrows to illustrate the ring-forming step of the mechanism.

Accepted Answer

The answer of The reaction below occurs by a general-acid...

Question 4

Give the first step for the mechanism for serine protease.

Accepted Answer

A) Histidine functions as a base , increasing the nucleophilicity of serine, which attacks the carbonyl group. 
B) The tetrahedral complex collapses, expelling the amino group. 
C) Water attacks the acyl group of the acyl-enzyme intermediate. 
D) The tetrahedral intermediate collapses, expelling serine. 
E) The negatively charged oxygen hydrogen bonds with two peptide bonds. 
A) Histidine functions as a base , increasing the nucleophilicity of serine, which attacks the carbonyl group. 
B) The tetrahedral complex collapses, expelling the amino group. 
C) Water attacks the acyl group of the acyl-enzyme intermediate. 
D) The tetrahedral intermediate collapses, expelling serine. 
E) The negatively charged oxygen hydrogen bonds with two peptide bonds.

Question 5

________ molarity is the concentration of the reactant that would be required to give the corresponding intermolecular reaction the same rate as its intramolecular counterpart.

Accepted Answer

A) Effective 
B) Entropic 
C) Enthalpic 
D) Hyperionic 
E) Deficient 
A) Effective 
B) Entropic 
C) Enthalpic 
D) Hyperionic 
E) Deficient

Question 6

What are NAM and NAG and what do they do?

Accepted Answer

NAM is N-acetylmuramic acid an

Question 7

List four common types of catalysts used in organic reactions and give one example of each.

Accepted Answer

The answer of List four common types of catalysts used...

Question 8

How does Zn2+ catalyze the hydrolysis of trifluoroacetate esters?

Accepted Answer

The interaction of Zn²⁺ with water yields

Question 9

How do enzymes differ from nonbiological catalysts?

Accepted Answer

A) They have specificity for the substrate. 
B) They have lower molecular weights than nonbiological catalysts. 
C) They require higher pressure to be functional. 
D) They require lower pH to be functional. 
E) They are more polar than nonbiological catalysts. 
A) They have specificity for the substrate. 
B) They have lower molecular weights than nonbiological catalysts. 
C) They require higher pressure to be functional. 
D) They require lower pH to be functional. 
E) They are more polar than nonbiological catalysts.

Question 10

Explain the large difference in the relative rates of the following hydrolysis reactions:

Accepted Answer

This large difference in the relative ra

Question 11

Which of the following are affected when an intramolecular catalyst is used?

Accepted Answer

A) number of collisions between the two per unit time 
B) fraction of collisions with sufficient energy 
C) fraction of collisions with proper orientation 
D) rate of the reaction 
E) all of the above 
A) number of collisions between the two per unit time 
B) fraction of collisions with sufficient energy 
C) fraction of collisions with proper orientation 
D) rate of the reaction 
E) all of the above

Question 12

Explain the phenomenon known as molecular recognition. Give an example.

Accepted Answer

Molecular recognition is the recognition

Question 13

Identify the factors that contribute to the catalytic ability of enzymes.

Accepted Answer

A) proper orientation of the reacting groups 
B) some amino acid side chain groups of the enzyme serve as catalysts 
C) some amino acid side chains stabilize transition states and intermediates 
D) metal ions in enzymes serve as catalysts 
E) all of the above 
A) proper orientation of the reacting groups 
B) some amino acid side chain groups of the enzyme serve as catalysts 
C) some amino acid side chains stabilize transition states and intermediates 
D) metal ions in enzymes serve as catalysts 
E) all of the above

Question 14

Which of the following statements is not true about catalysts?

Accepted Answer

A) They can increase the rate of a chemical reaction. 
B) They can change the mechanism of a chemical reaction. 
C) They are changed in a chemical reaction. 
D) They participate in a chemical reaction. 
E) They can decrease the activation energy of a chemical reaction. 
A) They can increase the rate of a chemical reaction. 
B) They can change the mechanism of a chemical reaction. 
C) They are changed in a chemical reaction. 
D) They participate in a chemical reaction. 
E) They can decrease the activation energy of a chemical reaction.

Question 15

How does an acid catalyst speed up the reaction below?

Accepted Answer

Protonating the aziridine's N atom incre

Question 16

Describe the acid-catalyzed second slow step in the hydrolysis of an ester.

Accepted Answer

A) The electron pair on oxygen forms double bond and alcohol is the leaving group. 
B) The base abstracts extra hydrogen from protonated alcohol. 
C) The oxygen of the carbonyl group abstracts a hydrogen from HB. 
D) Water attacks the carbonyl carbon and electron pair goes to oxygen. 
E) The oxygen on the alkoxy group abstracts a hydrogen from HB. 
A) The electron pair on oxygen forms double bond and alcohol is the leaving group. 
B) The base abstracts extra hydrogen from protonated alcohol. 
C) The oxygen of the carbonyl group abstracts a hydrogen from HB. 
D) Water attacks the carbonyl carbon and electron pair goes to oxygen. 
E) The oxygen on the alkoxy group abstracts a hydrogen from HB.

Question 17

Propose a step-by-step mechanism for the general-acid catalyzed reaction shown below:

Accepted Answer

The answer of Propose a step-by-step mechanism for the general-acid...

Question 18

Which of the following is/are true about base-catalysts?

Accepted Answer

A) They increase the rate of a reaction by removing a proton from a reactant. 
B) They increase the rate of a reaction by providing a pathway with a more stable transition state. 
C) They facilitate the formation of a negatively charged tetrahedral intermediate. 
D) A and B only 
E) A, B and C 
A) They increase the rate of a reaction by removing a proton from a reactant. 
B) They increase the rate of a reaction by providing a pathway with a more stable transition state. 
C) They facilitate the formation of a negatively charged tetrahedral intermediate. 
D) A and B only 
E) A, B and C

Question 19

Which of the following statements account for the remarkable catalytic ability of enzymes?

Accepted Answer

A) proper positioning and specificity of active site and substrate 
B) proper positioning of amino acid side chains that serve as catalytic groups 
C) ability of the groups on the enzyme to stabilize transition states 
D) A and B 
E) all of the above 
A) proper positioning and specificity of active site and substrate 
B) proper positioning of amino acid side chains that serve as catalytic groups 
C) ability of the groups on the enzyme to stabilize transition states 
D) A and B 
E) all of the above

Question 20

In what kind of acid catalysis is the proton transferred completely to the reactant before a subsequent slow step?

Accepted Answer

specific-a

Exam 23: Catalysis

Describe the reaction coordinate diagram for a specific-acid-catalyzed reaction.

Which of the following residues acts as a general-acid catalyst in aldolase but as a general-base catalyst in chymotrypsin?

The reaction below occurs by a general-acid catalyzed mechanism. Use curved arrows to illustrate the ring-forming step of the mechanism.

Give the first step for the mechanism for serine protease.

________ molarity is the concentration of the reactant that would be required to give the corresponding intermolecular reaction the same rate as its intramolecular counterpart.

What are NAM and NAG and what do they do?

List four common types of catalysts used in organic reactions and give one example of each.

How does Zn2+ catalyze the hydrolysis of trifluoroacetate esters?

How do enzymes differ from nonbiological catalysts?

Explain the large difference in the relative rates of the following hydrolysis reactions:

Which of the following are affected when an intramolecular catalyst is used?

Explain the phenomenon known as molecular recognition. Give an example.

Identify the factors that contribute to the catalytic ability of enzymes.

Which of the following statements is not true about catalysts?

How does an acid catalyst speed up the reaction below?

Describe the acid-catalyzed second slow step in the hydrolysis of an ester.

Propose a step-by-step mechanism for the general-acid catalyzed reaction shown below:

Which of the following is/are true about base-catalysts?

Which of the following statements account for the remarkable catalytic ability of enzymes?

In what kind of acid catalysis is the proton transferred completely to the reactant before a subsequent slow step?

Remembering General Chemistry: Electronic Structure and Bonding

Acids and Bases: Central to Understanding Organic Chemistry

An Introduction to Organic Compounds

Isomers: the Arrangement of Atoms in Space

Alkenes Thermodynamics and Kinetics

Reactions of Alkenes

Reactions of Alkynes Introduction to Multistep Synthesis

Electron Delocalization, Resonance, and Aromaticity More About Molecular Orbital Theory

Substitution Reactions of Alkyl Halides

Elimination Reactions of Alkyl Halides Competition Between Substitution and Elimination

Reactions of Alcohols, Ethers, Epoxides, and Sulfur-Containing Compounds

Organometallic Compounds

Reactions of Alkanes, Radicals

Mass Spectrometry, Infrared Spectroscopy, and Uvvis Spectroscopy

Nmr Spectroscopy

Reactions of Carboxylic Acids and Carboxylic Acid Derivatives

Reactions of Aldehydes and Ketones

Reactions at the Alpha Carbon of Carbonyl Compounds

Reactions of Benzene and Substituted Benzenes

More About Amines Heterocylic Compounds

Carbohydrates

Amino Acids, Peptides, and Proteins

The Organic Mechanisms of the Coenzymes

The Chemistry of Metabolism

Nucleosides, Nucleotides, and Nucleic Acids

Synthetic Polymers

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How does Zn²⁺ catalyze the hydrolysis of trifluoroacetate esters?