Enzymes and Catalysis

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What is the primary function of an enzyme?

To decrease the rate of a chemical reaction
To be consumed by the reactants
To alter the reactants in a chemical reaction
To increase the rate of a chemical reaction (correct)

What is the characteristic of enzyme-substrate binding according to the induced fit model?

The enzyme binds to multiple substrates simultaneously
The substrate induces a change in the enzyme's conformation (correct)
The enzyme-substrate complex is highly unstable
The enzyme's shape is complementary to the substrate's shape

What is the purpose of the active site in an enzyme-catalyzed reaction?

To increase the activation energy
To bind to the substrate by noncovalent interactions (correct)
To bind to the products
To bind to the reactants

Why is the lock-and-key model less likely to be an effective catalyst?

The ES complex may be too stable, reducing the thermodynamic benefit (B) Signup and view all the answers

What is the term for the energy required to reach the transition state from the ground state of the reactants?

Activation energy (A) Signup and view all the answers

What is the characteristic of enzyme-catalyzed reactions?

They are 103-1020 times faster than uncatalyzed reactions (D) Signup and view all the answers

What is the primary function of the transition state?

To represent an unstable arrangement of atoms in which chemical bonds are being formed or broken (A) Signup and view all the answers

What is the advantage of inducing a fit in the induced fit model?

It reduces the distance to the transition state (A) Signup and view all the answers

What is the characteristic of most enzymes?

They are proteins (D) Signup and view all the answers

What is the term for the reactant in an enzyme-catalyzed reaction?

Substrate (C) Signup and view all the answers

What is the characteristic of competitive inhibition?

Km increases (A) Signup and view all the answers

What is the effect of uncompetitive inhibition on Vmax?

Decreases (A) Signup and view all the answers

What is the characteristic of non-competitive inhibition?

Vmax decreases, Km remains the same (A) Signup and view all the answers

What is the effect of adding more substrate in competitive inhibition?

Overcomes the inhibition (D) Signup and view all the answers

What type of inhibition occurs when the inhibitor binds only to the ES complex?

Uncompetitive (D) Signup and view all the answers

What is the effect of non-competitive inhibition on Km?

Remains the same (B) Signup and view all the answers

What is the characteristic of irreversible inhibition?

Forms a stable covalent bond with the enzyme (C) Signup and view all the answers

What is the effect of uncompetitive inhibition on the ES complex?

Decreases the formation of ES (C) Signup and view all the answers

What is the result of irreversible inhibition of acetylcholinesterase (AChE)?

Death by paralysis (B) Signup and view all the answers

What is the difference between reversible and irreversible inhibition?

Reversible inhibition can be overcome by adding more substrate, while irreversible inhibition cannot (B) Signup and view all the answers

What is the primary purpose of studying Enzyme Kinetics?

To understand various properties of enzymes such as substrate specificity and affinity (A) Signup and view all the answers

What is the unit of measurement for Turnover Number (Kcat)?

sec-1 (B) Signup and view all the answers

What does a small KM value indicate?

The enzyme requires only a small amount of substrate to become saturated (C) Signup and view all the answers

What is the purpose of Lineweaver-Burk plots?

To accurately determine Vmax and KM from experimental data (A) Signup and view all the answers

What is the result of excessive heat on enzyme function?

Enzyme becomes completely nonfunctional (A) Signup and view all the answers

What type of inhibitor binds to the active site of E, competing with S?

Competitive inhibitor (D) Signup and view all the answers

What is the definition of Vmax?

The maximum reaction rate reached when the enzyme is completely saturated with substrate (A) Signup and view all the answers

What is the significance of Km in enzyme kinetics?

It gives us information on enzyme affinity for the substrate (A) Signup and view all the answers

What is the definition of catalytic efficiency?

The ratio of Kcat to Km (C) Signup and view all the answers

What is the effect of pH on enzyme function?

Enzymes work best within a particular range of pH (A) Signup and view all the answers