Enzymes Explained for AP Bio Students

Enzymes are typically proteins that catalyze reactions by lowering activation energy, thus increasing reaction rates. They are highly specific due to their active site complementing the substrate's shape and charge, and function optimally within a narrow range of conditions.

Most enzymes have an optimal pH at which they operate most efficiently. Deviations from this optimum pH disrupt the protein's bonds, leading to denaturation, which changes the active site's shape and reduces enzyme function by hindering substrate binding.

Up to a certain point, enzyme activity increases with temperature due to increased kinetic energy and molecular motion, enhancing enzyme-substrate encounters. However, beyond an optimal temperature, enzymes denature, permanently altering their shape and destroying their catalytic ability.

Reversible denaturation allows an enzyme to regain its optimal shape and function once optimal conditions are restored. Irreversible denaturation causes a permanent change in the enzyme's shape, leading to a complete loss of catalytic ability.

At low substrate concentrations, product formation is slow. As substrate concentration increases, so does the reaction rate, until a saturation point is reached where all enzyme active sites are occupied, and the reaction rate plateaus.

In competitive inhibition, a foreign molecule blocks the enzyme's active site, preventing substrate binding. In non-competitive inhibition, a foreign molecule binds to an allosteric site, inducing a conformational change in the active site, thereby diminishing or blocking enzyme activity.