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Questions and Answers
Why is it necessary for living systems to regulate enzyme activity?
Why is it necessary for living systems to regulate enzyme activity?
What happens when an enzyme continues to catalyze a reaction that produces a product present in plentiful amounts in a cell?
What happens when an enzyme continues to catalyze a reaction that produces a product present in plentiful amounts in a cell?
What type of inhibition is associated with controlling the availability of an enzyme?
What type of inhibition is associated with controlling the availability of an enzyme?
What is the result of covalent modifications to an enzyme's conformation or structure?
What is the result of covalent modifications to an enzyme's conformation or structure?
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Why is it necessary to 'turn off' an enzyme when its substrate concentration is very low?
Why is it necessary to 'turn off' an enzyme when its substrate concentration is very low?
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What is the purpose of regulating enzyme activity in a cell?
What is the purpose of regulating enzyme activity in a cell?
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What is the primary function of allosteric enzymes?
What is the primary function of allosteric enzymes?
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What is the result of a negative allosteric effector binding to an enzyme?
What is the result of a negative allosteric effector binding to an enzyme?
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What type of inhibition occurs when an inhibitor forms a strong covalent bond with the enzyme?
What type of inhibition occurs when an inhibitor forms a strong covalent bond with the enzyme?
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What is the purpose of feedback control in enzyme regulation?
What is the purpose of feedback control in enzyme regulation?
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What is the effect of an irreversible inhibitor on an enzyme?
What is the effect of an irreversible inhibitor on an enzyme?
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What is the role of zymogens in regulating enzyme activity?
What is the role of zymogens in regulating enzyme activity?
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What is the primary mechanism by which an enzyme recognizes its specific substrate?
What is the primary mechanism by which an enzyme recognizes its specific substrate?
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What is the advantage of the induced fit model over the lock-and-key model?
What is the advantage of the induced fit model over the lock-and-key model?
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Which of the following forces is responsible for drawing the substrate into the active site of an enzyme?
Which of the following forces is responsible for drawing the substrate into the active site of an enzyme?
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What is the term for the ability of an enzyme to choose an exact substrate from a group of similar chemical molecules?
What is the term for the ability of an enzyme to choose an exact substrate from a group of similar chemical molecules?
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What is the consequence of an enzyme having a geometric specificity?
What is the consequence of an enzyme having a geometric specificity?
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Which enzyme can oxidize both ethanol and methanol to yield corresponding aldehydes?
Which enzyme can oxidize both ethanol and methanol to yield corresponding aldehydes?
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Study Notes
Importance of Enzyme Regulation
- Living systems must regulate enzymatic catalytic activity to coordinate metabolic processes, adapt to environmental changes, and ensure proper growth and life cycles.
Mechanisms of Enzyme Regulation
- Control of enzyme availability through production of zymogens
- Control of enzymatic activity through covalent modifications of conformation or structure (irreversible inhibition)
- Feedback control associated with allosteric enzymes (noncompetitive inhibition)
Feedback Control
- Allosteric enzymes have two receptor sites: one for the substrate and one for an inhibitor or activator molecule
- Positive allosteric effectors increase enzyme activity, while negative allosteric effectors decrease it
- Feedback control involves the inhibition of the first enzyme in a pathway by the product of the reaction sequence
- This process shuts down the entire sequence when the end product accumulates
Irreversible Inhibition
- Irreversible inhibitors bind tightly or form strong covalent bonds with functional groups in the active site, permanently deactivating the enzyme
- Irreversible inhibition destroys the active site, decreasing the reaction rate
Applications of Inhibitors
- Negative feedback: end-point or end-product inhibition
- Medicine: antibiotics, sulphonamides, sedatives, and stimulants
- Poisons: snake bites, plant alkaloids, and nerve gases
Zymogens and Regulation
- Zymogens are inactive enzymes produced by cells, which can be activated as needed
- The active site of an enzyme has a fixed, rigid geometrical conformation complementary to the substrate
Enzyme Specificity
- Specificity is the ability of an enzyme to choose the exact substrate from a group of similar molecules
- Specificity operates through structural and conformational complementarity between enzymes and substrates
- Geometric specificity: a single enzyme can act on different substrates with similar molecular geometry, reducing specificity
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Description
This quiz covers the regulation of enzyme activity, including the role of allosteric enzymes, positive and negative allosteric effectors, and feedback control mechanisms.
