Enzyme Classification IUB System Quiz
40 Questions
14 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What does the first digit in an enzyme's EC number represent?

  • Subclass
  • Serial number
  • Sub-subclass
  • Class (correct)

Which of the following groups does a transferase enzyme typically act on?

  • Carbohydrates
  • Functional groups (correct)
  • Nucleotides
  • Lipids

What is the function of oxidoreductases?

  • Transfer electrons or hydrogen (correct)
  • Add or remove phosphate groups
  • Break down fats
  • Modify sugars into isomers

How many functional classes are enzymes divided into according to the IUB?

<p>6 (A)</p> Signup and view all the answers

Which of the following is an example of a lysase enzyme?

<p>Citrate lyase (D)</p> Signup and view all the answers

What does the second digit in an EC number signify?

<p>Subclass (B)</p> Signup and view all the answers

What type of reaction do hydrolases primarily catalyze?

<p>Hydrolysis reactions (D)</p> Signup and view all the answers

Which statement accurately describes the EC number format?

<p>Consists of four digits separated by decimal points (B)</p> Signup and view all the answers

What fundamental property of enzymes allows them to increase the rate of chemical reactions?

<p>They are not permanently altered by the reaction. (A)</p> Signup and view all the answers

What is the active site in enzyme catalysis?

<p>The localized site where the catalytic reaction occurs. (A)</p> Signup and view all the answers

How do enzymes influence activation energy in a reaction?

<p>They lower the activation energy required to reach the transition state. (C)</p> Signup and view all the answers

Which statement accurately describes enzyme catalysis?

<p>Enzymes increase reaction rates without being consumed. (C)</p> Signup and view all the answers

What is meant by the term 'transition state' in enzymatic reactions?

<p>The highest energy state that occurs during the reaction. (C)</p> Signup and view all the answers

Which of the following is a characteristic function of enzymes?

<p>They can speed up reactions in both forward and reverse directions. (D)</p> Signup and view all the answers

Which factor is crucial for enzyme catalysis?

<p>Reduction of energy barriers between reactants and products. (B)</p> Signup and view all the answers

What is the primary role of enzymes in living organisms?

<p>To increase the rate of chemical reactions. (D)</p> Signup and view all the answers

What is the primary role of enzymes in biochemical reactions?

<p>They accelerate reactions by lowering the activation energy. (B)</p> Signup and view all the answers

Why is the three-dimensional structure of enzymes important?

<p>It ensures they interact with their substrates effectively. (B)</p> Signup and view all the answers

Which of the following statements about enzyme cofactors is true?

<p>Cofactors can be either inorganic ions or organic molecules. (D)</p> Signup and view all the answers

Which option represents a common example of an enzyme that requires a cofactor?

<p>Cytochrome oxidase (D)</p> Signup and view all the answers

What happens to the overall change in free energy during an enzyme-catalyzed reaction?

<p>It remains unchanged. (D)</p> Signup and view all the answers

What type of enzyme structure is primarily responsible for the activity of most enzymes?

<p>Both tertiary and quaternary structures (D)</p> Signup and view all the answers

Which of the following metals is commonly found as a cofactor for enzymes?

<p>Zinc (B)</p> Signup and view all the answers

Cofactors are necessary because they typically assist enzymes in:

<p>Binding with substrates. (D)</p> Signup and view all the answers

What are enzymes primarily composed of?

<p>Amino acids (D)</p> Signup and view all the answers

How can environmental temperature affect enzyme activity?

<p>Temperature affects the movement of molecules. (B)</p> Signup and view all the answers

What happens to an enzyme when it exceeds its optimal temperature?

<p>It denatures and changes shape. (C)</p> Signup and view all the answers

What is the role of amino acid residues in an enzyme's active site?

<p>To create a chemical environment for substrate interaction. (B)</p> Signup and view all the answers

What is the effect of dramatic changes to temperature and pH on enzymes?

<p>They can cause enzymes to lose function. (D)</p> Signup and view all the answers

Which statement best describes the induced fit model of enzyme action?

<p>Enzymes undergo a slight shape change for optimal binding. (D)</p> Signup and view all the answers

What type of amino acid residue would contribute to a hydrophilic environment at the active site?

<p>Acidic residues that can form hydrogen bonds. (C)</p> Signup and view all the answers

Which of the following best defines the specificity of an enzyme?

<p>An enzyme typically reacts with only one substrate. (A)</p> Signup and view all the answers

Which of the following best describes the role of coenzymes in biochemical reactions?

<p>They facilitate the activity of enzymes. (D)</p> Signup and view all the answers

What fundamental change does an isomerase enzyme catalyze?

<p>Rearrangement of atomic grouping. (C)</p> Signup and view all the answers

Which type of enzyme is involved in converting a molecule from one isomeric form to another?

<p>Isomerase (D)</p> Signup and view all the answers

What is an isomer in the context of chemistry?

<p>A chemical compound with the same formula but distinct arrangements of atoms. (B)</p> Signup and view all the answers

Which option is NOT a type of enzyme mentioned in the content?

<p>Carboxylase (A)</p> Signup and view all the answers

Which of the following statements about isomerization is true?

<p>It involves converting between different isomeric forms. (B)</p> Signup and view all the answers

What is the consequence of an enzyme like an isomerase acting on a substrate?

<p>The substrate is transformed into a different isomer. (C)</p> Signup and view all the answers

Which coenzyme acts as a key component in several enzymatic reactions?

<p>5-Deoxyadenosylcobalamin (B)</p> Signup and view all the answers

Flashcards

Enzyme Classification System

The IUB system (International Union of Biochemistry) that categorizes enzymes into classes based on the type of reaction they catalyze.

EC Code

A numerical code assigned to enzymes to identify them and their specific function.

Oxidoreductases

Enzymes that catalyze oxidation-reduction reactions.

Transferases

Enzymes that transfer functional groups.

Signup and view all the flashcards

Hydrolases

Enzymes that catalyze hydrolysis reactions.

Signup and view all the flashcards

Lyases

Enzymes that catalyze addition or removal of groups to form double bonds.

Signup and view all the flashcards

Isomerases

Enzymes that catalyze isomerization reactions.

Signup and view all the flashcards

Ligases

Enzymes that join two molecules together.

Signup and view all the flashcards

Enzyme Catalysis

Enzymes speed up reactions without being consumed.

Signup and view all the flashcards

Active Site

The specific region on an enzyme where the substrate binds and the reaction occurs.

Signup and view all the flashcards

Activation Energy

The energy needed to start a reaction.

Signup and view all the flashcards

Induced Fit Model

The enzyme and substrate change shape slightly when they bind.

Signup and view all the flashcards

Cofactor

Non-protein molecules needed for enzyme activity.

Signup and view all the flashcards

Coenzyme

An organic cofactor.

Signup and view all the flashcards

Enzyme Specificity

An enzyme's ability to react with only certain molecules.

Signup and view all the flashcards

Enzyme Denaturation

Loss of function due to changes in the enzyme structure caused by extreme conditions

Signup and view all the flashcards

Temperature's effect on Enzymes

Increased temperature initially accelerates reactions but extreme temperatures result in denaturation.

Signup and view all the flashcards

pH's effect on Enzymes

Optimal pH range for enzyme activity.

Signup and view all the flashcards

Transition State

The unstable intermediate stage in a reaction.

Signup and view all the flashcards

Reaction Rate

The speed at which a reaction proceeds.

Signup and view all the flashcards

Equilibrium

The state where concentrations of reactants and products do not change anymore.

Signup and view all the flashcards

Substrate

The molecule an enzyme acts upon.

Signup and view all the flashcards

Enzyme Function

Accelerating chemical reactions without being spent or destroyed.

Signup and view all the flashcards

Study Notes

IUB System of Enzyme Classification

  • Enzymes are named and identified using the IUB system, which assigns an EC numerical code.
  • The EC code contains four digits: the first indicates the class, the second the subclass, the third the subgroup, and the fourth the specific enzyme identifier.
  • The EC number format is a.b.c.d, where "b" and "c" relate to reaction specifics, and "d" differentiates enzymes with similar functions based on substrate.

Classes of Enzymes

  • Enzymes are divided into six functional classes according to the International Union of Biochemistry (IUB):
    • Oxidoreductases: Catalyze oxidation/reduction reactions (e.g., Lactate dehydrogenase).
    • Transferases: Transfer functional groups, such as methyl or phosphate (e.g., Alanine transaminase).
    • Hydrolases: Catalyze hydrolysis reactions.
    • Lyases: Catalyze the addition or removal of groups to form double bonds.
    • Isomerases: Catalyze conversion between isomers.
    • Ligases: Join two molecules with covalent bonds.

Enzyme Catalysis

  • Enzymes increase reaction rates without being consumed or altered.
  • They do not affect the equilibrium of reactions, merely the speed.
  • Catalysis occurs at the enzyme's active site, which reduces the activation energy barrier to enhance product formation.
  • Enzymes facilitate reactions in both directions; they are recycled rather than changed during the reaction.

Energy and Enzymatic Reactions

  • Catalytic activity is characterized by enzymes lowering the energy required to reach the transition state.
  • The active site's structure results from the unique arrangements and properties of amino acid residues, impacting enzyme specificity.

Active Sites and Environmental Conditions

  • Reaction rates are influenced by environmental factors like temperature and pH.
  • Increasing temperature generally enhances reaction rates due to increased molecular movement; however, extreme conditions can lead to denaturation.
  • Denaturation alters the enzyme's structure, impeding substrate binding and reaction rates.

Induced Fit Model

  • The induced fit model proposes that the enzyme and substrate undergo a slight conformational change upon binding to optimize interaction.
  • This model highlights the importance of the enzyme's structure in facilitating reactions.

Cofactors and Coenzymes

  • Cofactors can be metal ions (e.g., Mg²⁺, Fe²⁺, Zn²⁺) or organic molecules (e.g., vitamins).
  • They assist enzymes in catalyzing biochemical reactions and are crucial for enzyme function.

Additional Notes on Enzymes

  • Enzymes accelerate reactions by lowering the activation energy and are usually proteins with complex 3D structures.
  • They remain unchanged post-reaction and do not affect the reaction's overall free energy change.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Related Documents

1.2 Enzyme Classification.pptx

Description

Test your knowledge on the IUB system of enzyme classification. This quiz covers the structure of EC codes, the six functional classes of enzymes, and examples for each class. Perfect for biology students looking to deepen their understanding of enzymology.

Use Quizgecko on...
Browser
Open
Browser
Browser