Practice Questions

If substrate is insufficient, additional enzyme molecules remain unused because there are not enough substrate molecules to occupy their active sites.

Constant pH allows accurate measurement of other variables by preventing changes in the enzyme's active site charge.

Trypsin is adapted to the alkaline environment of the small intestine, where its catalytic residues remain correctly ionized.

Pepsin functions optimally around pH 2 due to the highly acidic conditions of the stomach.

Correct protonation of amino acid side chains is essential for substrate binding and catalysis. Extreme pH alters these charges.

Heat primarily disrupts weak interactions such as hydrogen bonds, altering the shape of the active site and reducing enzyme activity.

Low temperature slows the movement of enzyme and substrate molecules, reducing effective collisions. The effect is generally reversible.

With substrate in excess, the reaction rate depends mainly on the number of enzyme molecules available to catalyze the reaction.

Maximum velocity (Vmax) is reached when every active site is occupied. Adding more substrate cannot further increase the reaction rate.

At low substrate concentrations, many enzyme active sites are unoccupied. Increasing substrate concentration increases the frequency of enzyme-substrate complex formation and accelerates the reaction.