Question

mini-quiz: temperature and enzymes
why does the reaction rate slow down drastically when the temperature is too high?
a. the enzyme and substrate get stuck together and cannot separate, resulting in a slower reaction.
b. the substrates are moving too fast for the enzyme.
c. the enzyme loses its color and attractiveness, rendering it useless.
d. the enzyme loses its shape (denatures) and can no longer effectively catalyze the reaction.

Explanation:

Enzymes are proteins, and high temperatures cause them to denature (lose their shape). The function of an enzyme depends on its specific shape (for example, the active - site shape which binds to the substrate). When an enzyme denatures, its active site (or other functional parts) changes, and it can no longer effectively catalyze the reaction.

• Option A: There is no scientific basis for the idea that enzyme and substrate “get stuck together” in this context. Enzyme - substrate binding is based on specific interactions (like lock - and - key or induced - fit models), not random “sticking” that cannot be resolved.
• Option B: While increased temperature does increase the kinetic energy of substrates (they move faster), the main issue at high temperatures is enzyme denaturation, not just substrate movement relative to the enzyme.
• Option C: Enzyme function is not related to color. Enzymes are biological catalysts, and their catalytic activity is due to their molecular structure (not color).

Answer:

D. The enzyme loses its shape (denatures) and can no longer effectively catalyze the reaction.