GPAT Practice Quiz

Question 1

In Michaelis-Menten kinetics, the Michaelis constant (Km) is defined as the substrate concentration at which:

Accepted Answer

the reaction velocity is half of Vmax

Question 2

For an enzyme following Michaelis-Menten kinetics, what is the effect of increasing enzyme concentration while keeping substrate concentration constant and non-limiting?

Accepted Answer

Vmax increases proportionally

Question 3

An enzyme obeys Michaelis-Menten kinetics with Km = 2 mM. At what substrate concentration will the initial velocity be 80% of Vmax?

Accepted Answer

8 mM

Question 4

For the mechanism E + S ⇌ ES → E + P, which expression correctly gives the Michaelis constant Km?

Accepted Answer

(k-1 + k2)/k1

Question 5

For the mechanism E + S ⇌ ES → E + P, if k-1 is much greater than k2, Km is best approximated by:

Accepted Answer

k-1/k1

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