Biochemistry Chapter on Enzymes

Questions and Answers

What is the primary function of enzymes in a chemical reaction?

They accelerate the rate of the reaction. (correct)

They get used up during the reaction.

They change the reaction products.

They alter the pH of the reaction.

Enzymes are least effective when conditions are optimal.

False

What is formed during the catalytic event of an enzyme action?

Enzyme-substrate complex

Enzymes reduce the energy needed to initiate __________ reactions.

spontaneous Signup and view all the answers

Match the following enzymes with their types:

Pepsin = Endopeptidase Aminopeptidase = Exopeptidase Chymotrypsin = Endopeptidase Carboxypeptidase = Exopeptidase Signup and view all the answers

What is the primary function of enzymes?

To act as biological catalysts Signup and view all the answers

Enzymes are consumed during the reactions they catalyze.

False Signup and view all the answers

What is the term used to describe the region of the enzyme where the substrate binds?

Active site Signup and view all the answers

Enzymes exhibit __________ specificity, meaning they catalyze a single reaction or closely related reactions.

reaction Signup and view all the answers

Match the enzyme to its feature:

Carbonic anhydrase = Speed up the reaction of CO2 and H2O Lysozyme = Acts on peptidoglycan Amylase = Breaks down starch DNA polymerase = Synthesize DNA strands Signup and view all the answers

Which of the following statements about enzyme activity conditions is true?

Enzymes have optimal temperature and pH conditions. Signup and view all the answers

The active site of an enzyme is always a large region of the enzyme.

False Signup and view all the answers

What phenomenon refers to the ability of the enzyme to preferentially bind one molecule over others?

Specificity Signup and view all the answers

What does the Michaelis-Menten constant (KM) indicate?

The concentration of substrate at which half of the active sites are filled Signup and view all the answers

What is the role of prosthetic groups?

To assist enzymes during catalysis by binding tightly Signup and view all the answers

A high KM value suggests a strong binding between substrate and enzyme.

False Signup and view all the answers

Apoenzyme is the active form of an enzyme.

False Signup and view all the answers

What happens to the rate of catalysis as substrate concentration ([S]) increases?

The rate of catalysis rises linearly and then levels off. Signup and view all the answers

What term is used for an enzyme combined with its cofactor?

Holoenzyme Signup and view all the answers

At ___________, enzyme molecules are almost all occupied.

Vmax Signup and view all the answers

Match the types of enzymes with their definitions:

Apoenzymes = Enzymes without their cofactors Holoenzymes = Enzymes with their cofactors Prosthetic groups = Tightly-bound cofactors Coenzymes = Loosely-bound organic cofactors Signup and view all the answers

Succinate dehydrogenase requires _____ as a cofactor.

FADH2 Signup and view all the answers

Which of these enzymes is classified as a Transferase?

Glycerokinase Signup and view all the answers

Which of the following describes Michaelis-Menten kinetics?

The relationship between reaction rate and substrate concentration Signup and view all the answers

Allosteric enzymes obey Michaelis-Menten kinetics.

False Signup and view all the answers

An increase in substrate concentration always leads to a linear increase in the reaction rate.

False Signup and view all the answers

What is the primary role of coenzymes?

They serve as loosely-bound organic cofactors. Signup and view all the answers

What type of reaction do oxidoreductases catalyze?

Oxidation-reduction Signup and view all the answers

Lyases catalyze reactions involving the _____ or removal of groups.

addition Signup and view all the answers

The reaction mechanism involves the formation of an ____________ complex.

enzyme-substrate Signup and view all the answers

Match the enzyme classifications with their examples:

Hydrolases = Carboxypeptidase A Ligases = Pyruvate carboxylase Isomerases = Maleate isomerase Oxidoreductases = Alcohol dehydrogenase Signup and view all the answers

What does Vmax represent in enzyme kinetics?

The maximum rate of reaction Signup and view all the answers

Michaelis-Menten kinetics can be applied to enzymes that do not follow a hyperbolic saturation curve.

False Signup and view all the answers

What is a common feature of allosteric enzymes?

They show cooperative binding. Signup and view all the answers

Cofactors can only be organic compounds.

False Signup and view all the answers

What is the main difference between simple enzymes and holoenzymes?

Simple enzymes lack cofactors, while holoenzymes include them. Signup and view all the answers

What is the primary function of ligases?

Joining two molecules together Signup and view all the answers

KM is a measure of the __________ of the enzyme-substrate complex.

strength Signup and view all the answers

An enzyme's name often ends in _____ to indicate its function.

ase Signup and view all the answers

Match the following terms with their definitions:

S = Substrate concentration Vo = Initial reaction velocity KM = Michaelis-Menten constant Vmax = Maximum reaction rate Signup and view all the answers

What type of reaction do hydrolases catalyze?

Hydrolytic cleavage Signup and view all the answers

Study Notes

Enzymes Overview

Enzymes are proteins that act as biological catalysts, accelerating biochemical reactions significantly.
They exhibit high specificity, catalyzing either a single reaction or closely related reactions.

Properties of Enzymes

Enzymes are globular proteins with a three-dimensional shape that determines function.
They lower the activation energy needed for reactions, thus speeding up the process without being consumed.
Each enzyme has an active site specific to its substrate, where the conversion of substrates to products occurs.

Mechanism of Enzyme Action

Carbonic anhydrase demonstrates enzyme efficiency, accelerating the reaction from CO2 and H2O to H2CO3 from 0.13 to 1,000,000 molecules per second.
The active site, a small cluster of amino acids, creates a microenvironment for substrate binding and catalysis.

Enzyme Specificity and Affinity

Specificity refers to an enzyme's ability to preferentially bind to a specific substrate.
Affinity measures the strength of the binding interaction between enzyme and substrate.

Enzyme Sensitivity and Optimal Conditions

Enzymes operate best under optimal conditions regarding temperature, pH, and salt concentration.
Variability in enzyme sensitivity impacts their effectiveness across different environments.

Catalytic Process

Enzymes facilitate the formation of a transition state through the formation of an enzyme-substrate complex (ES).
They change the reaction rate but not the reaction itself.

Enzyme Kinetics

Michaelis-Menten kinetics studies the relationship between substrate concentration and reaction velocity (V0).
Vmax indicates the maximum reaction rate achieved by an enzyme at saturation point when most active sites are occupied.
The Michaelis-Menten constant (KM) defines substrate concentration required for half-maximal velocity, indicating binding strength.

Enzymes and Cofactors

Many enzymes, known as holoenzymes, require cofactors for activity.
Cofactors can be organic (coenzymes like vitamins) or inorganic (metal ions such as Zn2+).
Apoenzymes refer to the inactive protein portion of an enzyme without its cofactor.

Allosteric Regulation

Allosteric enzymes possess multiple binding sites; substrate binding can influence the activity of other sites.
They do not follow simple Michaelis-Menten kinetics and often exhibit a sigmoidal reaction rate curve.

Classification of Enzymes

Enzymes are classified based on the reaction type they catalyze and commonly end in "ase."
Major classes include:
- Oxidoreductases: Involved in oxidation-reduction reactions (e.g., alcohol dehydrogenase).
- Transferases: Transfer functional groups between molecules (e.g., glycerokinase).
- Isomerases: Rearrange functional groups within a molecule (e.g., maleate isomerase).
- Hydrolases: Catalyze hydrolytic cleavage (e.g., carboxypeptidase A).
- Lyases: Add or remove groups form molecules (e.g., pyruvate decarboxylase).
- Ligases: Join two molecules together (e.g., pyruvate carboxylase).

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Description

This quiz covers the specificity and binding affinities of enzymes, focusing on endopeptidases and exopeptidases. Test your knowledge on the structure and function of various enzymes, including pepsin, chymotrypsin, and trypsin. Gain a deeper understanding of enzyme kinetics and peptide bonds.

Biochemistry Chapter on Enzymes

Questions and Answers

What is the primary function of enzymes in a chemical reaction?

Enzymes are least effective when conditions are optimal.

What is formed during the catalytic event of an enzyme action?

Enzymes reduce the energy needed to initiate __________ reactions.

Match the following enzymes with their types:

What is the primary function of enzymes?

Enzymes are consumed during the reactions they catalyze.

What is the term used to describe the region of the enzyme where the substrate binds?

Enzymes exhibit __________ specificity, meaning they catalyze a single reaction or closely related reactions.

Match the enzyme to its feature:

Which of the following statements about enzyme activity conditions is true?

The active site of an enzyme is always a large region of the enzyme.

What phenomenon refers to the ability of the enzyme to preferentially bind one molecule over others?

What does the Michaelis-Menten constant (KM) indicate?

What is the role of prosthetic groups?

A high KM value suggests a strong binding between substrate and enzyme.

Apoenzyme is the active form of an enzyme.

What happens to the rate of catalysis as substrate concentration ([S]) increases?

What term is used for an enzyme combined with its cofactor?

At ___________, enzyme molecules are almost all occupied.

Match the types of enzymes with their definitions:

Succinate dehydrogenase requires _____ as a cofactor.

Which of these enzymes is classified as a Transferase?

Which of the following describes Michaelis-Menten kinetics?

Allosteric enzymes obey Michaelis-Menten kinetics.

An increase in substrate concentration always leads to a linear increase in the reaction rate.

What is the primary role of coenzymes?

What type of reaction do oxidoreductases catalyze?

Lyases catalyze reactions involving the _____ or removal of groups.

The reaction mechanism involves the formation of an ____________ complex.

Match the enzyme classifications with their examples:

What does Vmax represent in enzyme kinetics?

Michaelis-Menten kinetics can be applied to enzymes that do not follow a hyperbolic saturation curve.

What is a common feature of allosteric enzymes?

Cofactors can only be organic compounds.

What is the main difference between simple enzymes and holoenzymes?

What is the primary function of ligases?

KM is a measure of the __________ of the enzyme-substrate complex.

An enzyme's name often ends in _____ to indicate its function.

Match the following terms with their definitions:

What type of reaction do hydrolases catalyze?

Study Notes

Enzymes Overview

Properties of Enzymes

Mechanism of Enzyme Action

Enzyme Specificity and Affinity

Enzyme Sensitivity and Optimal Conditions

Catalytic Process

Enzyme Kinetics

Enzymes and Cofactors

Allosteric Regulation

Classification of Enzymes

Studying That Suits You

Description

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