Biochem 4.2 Enzyme Classification and Transferase Quiz
48 Questions
0 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

Which class of enzymes primarily catalyzes the transfer of phosphate groups from ATP to substrates?

  • Hydrolases
  • Oxidoreductases
  • Phosphatases
  • Kinases (correct)

    • What is a major limitation of early enzyme classification based on the suffix --ase?

  • It fails to describe the catalytic mechanisms accurately. (correct)
  • It does not account for enzymes with mixed functions.
  • It ignores the substrate specificity of enzymes.
  • It mistakenly groups all enzymes under one category.

    • Which class of enzymes is responsible for breaking apart substrates by adding a phosphate group?

  • Ligases
  • Kinases
  • Phosphatases
  • Phosphorylases (correct)

    • How are the major classes of enzymes organized according to the Enzyme Commission classification system?

    <p>Based on their catalytic mechanisms</p> Signup and view all the answers

    What was added to enzyme classification in 2018?

    <p>A seventh class of enzymes</p> Signup and view all the answers

    Which of the following is NOT a function of oxidoreductases?

    <p>Aiding in phosphorylation reactions</p> Signup and view all the answers

    What is the main reason enzymes may have been reclassified over time?

    <p>Discovery of new catalytic mechanisms</p> Signup and view all the answers

    Which of the following correctly matches an enzyme class with its action?

    <p>Kinases - Transfer phosphate groups</p> Signup and view all the answers

    What is the primary function of transferase enzymes?

    <p>To catalyze the transfer of a functional group between two molecules.</p> Signup and view all the answers

    Which of the following statements is true regarding substrates in transferase reactions?

    <p>One substrate acts as a donor and the other as an acceptor.</p> Signup and view all the answers

    How do transferases differ from hydrolases?

    <p>Hydrolases involve water as an acceptor, while transferases do not.</p> Signup and view all the answers

    What distinguishes acyltransferases from other transferases?

    <p>They move fatty acyl groups from one molecule to another.</p> Signup and view all the answers

    What is a common characteristic of transferase reactions?

    <p>They produce two products after the transfer of functional groups.</p> Signup and view all the answers

    Which of the following is NOT an example of a transferase reaction?

    <p>Hydrolase catalyzing the breakdown of a triglyceride.</p> Signup and view all the answers

    Which functional group is commonly transferred by methyltransferases?

    <p>Methyl (–CH3) groups</p> Signup and view all the answers

    In transferase reactions, what role does the functional group donor play?

    <p>It loses a functional group and may become oxidized.</p> Signup and view all the answers

    What is the primary function of receptor enzymes?

    <p>To bind ligands and trigger intracellular effects</p> Signup and view all the answers

    What happens when an agonist binds to a receptor enzyme?

    <p>It activates its intracellular catalytic domain</p> Signup and view all the answers

    Which type of residues do receptor tyrosine kinases (RTKs) phosphorylate when activated?

    <p>Tyrosine residues</p> Signup and view all the answers

    What is an important feature of receptor tyrosine kinases regarding their structure?

    <p>They typically become dimers upon agonist binding</p> Signup and view all the answers

    What allows phosphotyrosine (pTyr) to act as a potent intracellular signal?

    <p>Its relative scarcity makes it a unique signal</p> Signup and view all the answers

    What process is involved in downstream signal propagation mediated by pTyr?

    <p>Recruitment and activation of downstream effectors</p> Signup and view all the answers

    Which two types of enzymes do most receptor enzymes belong to?

    <p>Kinases and guanylyl cyclases</p> Signup and view all the answers

    How does the catalytic domain of receptor enzymes typically behave until an agonist binds?

    <p>It is inactive</p> Signup and view all the answers

    What do kinases primarily transfer to a substrate molecule?

    <p>γ-phosphate group from ATP</p> Signup and view all the answers

    What is the main function of phosphorylases in biochemical reactions?

    <p>To break apart molecules using phosphate groups</p> Signup and view all the answers

    Which of the following is an example of a reaction catalyzed by transaminases?

    <p>Transfer of an α-amine group from an amino acid</p> Signup and view all the answers

    In the reaction catalyzed by glycogen phosphorylase, which compound acts as the acceptor?

    <p>Inorganic phosphate (Pi)</p> Signup and view all the answers

    Which of the following statements best describes the behavior of polymerases?

    <p>They transfer nucleotides onto a growing nucleic acid chain.</p> Signup and view all the answers

    What is the primary difference between phosphorolysis and hydrolysis?

    <p>Phosphorolysis does not involve water.</p> Signup and view all the answers

    Which type of enzyme is involved in transferring the γ-phosphate group in the reverse reaction of phosphorylation?

    <p>Kinases</p> Signup and view all the answers

    Why are transaminases considered transferases even though their reactions can be considered redox reactions?

    <p>Their primary function is transferring the amine group.</p> Signup and view all the answers

    What reaction does a mutase catalyze?

    <p>Transfer of a functional group within a molecule</p> Signup and view all the answers

    Which of the following describes configurational isomers?

    <p>They have the same molecular formula but different atom placement</p> Signup and view all the answers

    What is a characteristic feature of protein disulfide isomerases?

    <p>They move disulfide bonds within the same molecule</p> Signup and view all the answers

    What type of configuration do most peptide bonds favor?

    <p>Trans configuration</p> Signup and view all the answers

    What is the role of phosphoglycerate mutase in glycolysis?

    <p>It moves a phosphate group from one carbon to another on the same molecule</p> Signup and view all the answers

    Which statement about aldoses and ketoses is true?

    <p>Isomerases catalyze their interconversion</p> Signup and view all the answers

    Why can proline residues in peptide bonds exist in both cis and trans configurations?

    <p>They possess a unique ring structure that allows flexibility</p> Signup and view all the answers

    What is a typical feature of a redox process facilitated by certain isomerases?

    <p>They involve the transfer of disulfide bonds within a single molecule</p> Signup and view all the answers

    What type of reaction do hydrolases catalyze?

    <p>Reaction that involves breaking bonds using water</p> Signup and view all the answers

    Which of the following statements about proteases is correct?

    <p>Some proteases have common names that do not end in --ase.</p> Signup and view all the answers

    How can hydrolases typically be identified?

    <p>By examining the chemical equations of the reactions they catalyze</p> Signup and view all the answers

    What differentiates polymerases from ligases?

    <p>Polymerases incorporate nucleotides while ligases use them independently.</p> Signup and view all the answers

    Which enzyme is specifically known for hydrolyzing phosphate groups?

    <p>Phosphatase</p> Signup and view all the answers

    Which of the following best describes the action of kinases?

    <p>They add a phosphate group to substrates.</p> Signup and view all the answers

    What is a characteristic of most hydrolases in terms of naming?

    <p>They indicate the substrate they act on also with the suffix --ase.</p> Signup and view all the answers

    Which reaction is an example of a hydrolysis reaction catalyzed by hydrolases?

    <p>Breaking down a disaccharide into two monosaccharides.</p> Signup and view all the answers

    Study Notes

    Enzyme Classification

    • Enzymes catalyze a wide range of biochemical reactions on various substrates, producing diverse products.
    • Enzyme classification groups enzymes based on the type of reaction they catalyze.
    • An early system named enzymes based on their reaction and added the suffix "-ase".
    • This system has limitations, as it doesn't always clearly categorize enzymes with similar reactions but different mechanisms.
    • In 1961, the Enzyme Commission classified enzymes into six major classes based on their catalytic mechanism.
    • A seventh class was added in 2018.
    • Enzyme classification is important for understanding the catalytic mechanisms of enzymes.

    Oxidoreductases

    • Oxidoreductases catalyze oxidation-reduction reactions, transferring electrons between molecules.
    • These enzymes are multisubstrate, requiring both an electron donor and acceptor.
    • Redox cofactors or coenzymes (e.g., NAD+/NADH, FAD/FADH2) often change oxidation state during the reaction.
    • Crucial in many metabolic pathways.
    • The name often reflects the substrate changed.

    Transferases

    • Transferases catalyze the transfer of a functional group from one molecule (donor) to another (acceptor).
    • They typically require two substrates (donor and acceptor).
    • Water cannot be the acceptor.
    • Includes kinases (transfer phosphate groups), acyltransferases (transfer fatty acyl groups) and glycosyltransferases (transfer carbohydrates).
    • Important for metabolic processes involving functional group transfer.

    Hydrolases

    • Hydrolases catalyze the cleavage of a bond with the addition of water.
    • The reaction involves breaking a bond and adding water.
    • Important in many metabolic pathways for breaking down large molecules.
    • Named after the substrate or the functional group acted upon (e.g., esterases, glycosidases).

    Lyases

    • Lyases catalyze the addition or removal of a functional group to/from a double bond.
    • Do not use hydrolysis or redox rxns.
    • Include mechanisms involving elimination reactions or addition across double bonds.
    • Examples include enzymes involved in, glycolysis, fumarate hydratase.

    Isomerases

    • Isomerases catalyze reactions that change the structure of a single substrate without altering its net composition and type of atoms.
    • These reactions can result in constitutional or configurational isomers.
    • Examples include triose phosphate isomerase, mutases.

    Ligases

    • Ligases catalyze the joining of two molecules using the hydrolysis of ATP (or other nucleoside triphosphates).
    • This reaction involves joining two molecules (synthases).
    • Important in processes requiring energy investment to create a new bond between two molecules (e.g., in DNA repair or synthesis).
    • Names frequently include "synthetase" or "ligase."

    Studying That Suits You

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

    Quiz Team

    Related Documents

    Enzyme Classification - Biochemistry PDF

    Description

    Test your knowledge on enzyme classification, particularly focusing on transferases and their functions. This quiz covers key concepts, limitations, and updates in enzyme classification systems. Perfect for students studying biochemistry or related life sciences.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser