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Questions and Answers
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 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?
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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?
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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?
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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?
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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?
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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?
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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?
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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?
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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.
