Question

The efficiency of enzyme catalysis is due to its capacity to :
A. Form a strong enzyme substance complex
B. Change the shape of the substrate
C. Lower the activation energy of the reaction
D. Form a colloidal solution in water

Answer 1

Hint: Enzymes are protein molecules present in the living system. They are highly efficient biological catalysts that catalyse the reactions taking place in the living cells and also help in controlling their reaction rates.

Complete Step by Step Answer:
The reaction in enzyme catalysis happens at a distinct location on the protein molecule. This is named the active site. The reactants in an enzyme reaction are the substrates.

Some examples of enzyme-catalysed reactions are:
I) The conversion of starch into maltose in the presence of the diastase enzyme.
II) The conversion of maltose into glucose in the presence of the maltase enzyme.

The mechanism of an enzyme reaction was proposed by Michalis and Menten. This is as follows:
The long chains of the enzyme molecules are coiled to make a rigid colloidal particle with cavities on its surface. These cavities have characteristic shapes and are rich in active groups and are known as active centres. The molecules of the substrate which have complementary shapes fit into these cavities just as a key fits into a lock.

With the aid of active groups, the enzyme builds an activated complex with the substrate which disintegrates to generate the products. The efficiency of enzyme catalysis is due to its ability to diminish the activation energy of the reaction. Enzymes like any other catalyst reduces the activation energy of the reactants. It decreases the energy barrier and thus makes the reaction faster.
So, option C is correct.

Additional Information:The efficiency of enzyme catalysis is very high i.e Many of them are so powerful catalysts that they increase the rate of reaction by many orders of magnitude even at quite low concentrations. These are highly specific in their catalytic action. For example, urease even in very low concentrations catalyses urea like methyl urea.

Note: The activity of the enzyme is usually found to be maximum at the normal temperature of the organism in which the enzyme is found. Above the temperature, usually, the activity is first found to increase temporarily and then drops to zero when the protein is denatured.