Question

The “lock and key” model of enzyme action illustrates that a particular enzyme molecule
A. May be destroyed and resynthesized several times
B. Interacts with a specific type of substrate molecule
C. Reacts at identical rates under all conditions
D. Forms a permanent enzyme-substrate complex

Answer 1

Hint: Only a specific key with a specific pattern can open a lock.
Enzymes are proteins which regulates the rate at which the chemical reaction is processed.
It alters the speed of reaction and acts as a catalyst which speeds up the reaction, without being altered.

Complete step by step answer:
-The enzymes act on the substrate.
-There are several classes of enzymes based on which reaction they undergo and there are different enzymes which suit different substrates.
-Enzymes are specific to the substrate which has to be altered to the product.
-One of the modes of enzyme action is the “lock and key” model.
-Where the enzyme acts as the key which can be activated by a specific substrate, which is the key.
-Only the specific substrate for which the enzyme acts, can fit into the active site.
-This active site in the enzyme makes changes or alters the substrate into the product.

Hence the correct option is “B”.

Additional information:
 The “lock and key” model of enzyme action was first postulated by Emil Fischer in 1894. Another model of enzyme action is the “induced fit” model.

Note:
The enzymes are specific molecules. The absence of the specific enzyme may lead to the non-conversion of substrate to product. Enzyme-substrate complex is never permanent. After the conversion of substrate into the product, the product molecule is released since it no longer fits in the active site. The enzyme is free after the product formation and can be reused.