If you add sucrose to catalase when testing for reactivity, do you expect to see a reaction?
Multiple Choice
Yes, because catalase binds all chemicals
Yes, because catalase is an enzyme that increases any reaction rate.
No, because catalase is specific to sucrose
No, because catalase is specific to hydrogen peroxide.
The Correct Answer and Explanation is:
Correct Answer:
No, because catalase is specific to hydrogen peroxide.
Explanation
Catalase is a highly specific enzyme that catalyzes the decomposition of hydrogen peroxide (H₂O₂) into water (H₂O) and oxygen gas (O₂). The reaction it facilitates is:
2H2O2→2H2O+O22H_2O_2 \rightarrow 2H_2O + O_2
This specificity arises from the unique structure of catalase’s active site, which is shaped precisely to bind hydrogen peroxide molecules. Enzymes are not general-purpose catalysts—they are substrate-specific, meaning they only catalyze reactions involving certain molecules that fit their active site. The principle behind this is often compared to a “lock and key” mechanism, where only the right key (substrate) fits the lock (enzyme).
Sucrose, on the other hand, is a disaccharide sugar composed of glucose and fructose. It does not resemble hydrogen peroxide in structure or chemical properties. Since sucrose does not fit the active site of catalase, the enzyme cannot bind to or act on sucrose. Therefore, no reaction would occur if sucrose were added to catalase in the absence of hydrogen peroxide.
If a reaction were expected with sucrose, it would require a different enzyme altogether—sucrase (also known as invertase)—which specifically breaks down sucrose into its component monosaccharides.
The other options in the multiple-choice question are incorrect because:
- “Yes, because catalase binds all chemicals” is false—enzymes do not bind all chemicals.
- “Yes, because catalase is an enzyme that increases any reaction rate” is incorrect—enzymes are highly specific to particular reactions.
- “No, because catalase is specific to sucrose” is incorrect—catalase is not specific to sucrose; it is specific to hydrogen peroxide.
In conclusion, catalase only reacts with hydrogen peroxide, and adding sucrose will not trigger any enzymatic reaction.
