9700 · 3.1
Mode of action of enzymes flashcards
Revision flashcards for Cambridge 9700 Mode of action of enzymes (syllabus 3.1). Flip, recall, then mark a real past-paper question.
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What is an enzyme?
A globular protein that acts as a biological catalyst, speeding up the rate of a specific biochemical reaction without being consumed in the process.
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What is activation energy?
The minimum amount of energy that must be supplied to reactants for a chemical reaction to occur.
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How do enzymes accelerate reactions?
By providing an alternative reaction pathway that has a lower activation energy, thus increasing the rate of reaction.
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Describe the active site of an enzyme.
A specific three-dimensional region on the enzyme's surface, with a shape and chemical properties complementary to its substrate, where catalysis occurs.
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What is the induced-fit model of enzyme action?
A model suggesting the enzyme's active site is flexible and changes shape slightly upon substrate binding to achieve a more precise fit, straining the substrate's bonds.
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What is an enzyme-substrate complex (ESC)?
A temporary structure formed when a substrate molecule binds to the active site of an enzyme.
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State the general equation for an enzyme-catalysed reaction.
E + S ⇌ ES → E + P (E=Enzyme, S=Substrate, P=Product)
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What is meant by the term 'turnover number' (k_cat)?
The maximum number of substrate molecules a single enzyme molecule can convert to product per unit of time when saturated with substrate. It's a measure of catalytic efficiency.