Question 1

For the generalized reaction $$aA + bB \rightarrow cC + dD$$, which of the following correctly expresses the initial rate of consumption of A ($$V_0) in $$terms of the concentrations of A and B?

Accepted Answer

$$V_0 = k$$[A]^x[B]^y$$

Question 2

Which graphical feature best represents the initial rate ($$V_0) of a $$reaction when plotting $$[A]$$ versus time?

Accepted Answer

The slope of the tangent to the curve at $$t=0$$

Question 3

A reaction is found to be first order with respect to $$A. $$Which of the following best describes the plot of $$[A]$$ versus time?

Accepted Answer

An exponential decay curve

Question 4

For a second-order reaction with respect to $$A$$, which equation correctly describes the relationship between $$[A]$$ and time?

Accepted Answer

$$\frac{1}{[A]} = kt + \frac{1}{[A]_0}$$

Question 5

In the Michaelis-Menten equation, what does $$K_m$$ represent?

Accepted Answer

The substrate concentration at which the reaction rate is half of $$V_{max}$$

Question 6

Which of the following is the correct Michaelis-Menten equation for the initial velocity $$V_0$$?

Accepted Answer

$$V_0$$ = \frac{V_{max}[S]}{K_m + [S]}$$

Question 7

If $$[S] \gg K_m$$, what is the order of the Michaelis-Menten reaction with respect to substrate $$S$$?

Accepted Answer

Zero order

Question 8

What is the definition of $$k_{cat} ($$turnover number) in enzyme kinetics?

Accepted Answer

The rate constant for the slowest chemical step in the reaction mechanism

Question 9

Which of the following best describes the steady-state assumption in enzyme kinetics?

Accepted Answer

The concentration of the enzyme-substrate complex remains constant over time

Question 10

In a Lineweaver-Burk plot of $$\frac{1}{V_0$}$$ versus $$\frac{1}{[S]}$$, what is the slope of the line?

Accepted Answer

$$\frac{K_m}{V_{max}}$$

Question 11

Why is $$k_{cat}/K_m ($$the specificity constant) considered an important parameter for comparing different enzymes?

Accepted Answer

It reflects both the catalytic efficiency and substrate binding affinity

Question 12

If $$k_{-1} \ll k_2$, what does K_m$ approximate?

Accepted Answer

$$K_m \approx K_d ($$the dissociation constant for ES)

Question 13

Which of the following statements about reversible enzyme inhibitors is TRUE?

Accepted Answer

Uncompetitive inhibitors only bind to the ES complex

Question 14

What is the physiological advantage of an enzyme whose reaction rate is highly sensitive to substrate concentration near $$K_m$$?

Accepted Answer

Small changes in substrate concentration can rapidly alter the reaction rate, allowing for tight regulation

Question 15

Which of the following is TRUE regarding the effect of decreasing $$[B] in $$the reaction $$aA + bB \rightarrow cC + dD if $$the rate law is $$V_0 = k$$[A]^x[B]^y$$?

Accepted Answer

The rate will decrease if $$y \u003e 0$$

Question 16

What is the unit of $$K_m in $$the Michaelis-Menten equation?

Accepted Answer

Molarity ($$M)$$

Question 17

Which of the following best describes $$V_{max} in $$terms of enzyme concentration?

Accepted Answer

$$V_{max} = k_{cat}[E]_t$$

Question 18

Why is the highest possible value of the specificity constant $$k_{cat}/K_m$$ about $$10^8$$ $$M^{-1}s$$^{-1}$?

Accepted Answer

It is limited by the rate of diffusion of substrate to the active site

Question 19

In the Michaelis-Menten mechanism, which step is usually considered rate-limiting?

Accepted Answer

The chemical step converting ES to E + P

Chemical Kinetics and Enzyme Catalysis: Study Notes

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