Answer: The correct option is (the region of an enzyme that attaches to a substrate).
Step-by-step explanation:
The anabolic and catabolic processes in a cell are directed and regulated by enzymes. An enzyme has the ability to speed up a metabolic reaction by lowering the amount of energy needed to start the reaction. Without enzymes, these processes would be extremely slow. They also arrange the reacting molecules in a manner that will cause the chemical change to take place rapidly. It does so through the following steps:
--> molecules of substrate combine with the enzyme at its active site.
--> the substrate molecules combine with enzyme molecules for a short time, forming an enzyme-substrate complex.
--> New substance ( product) is formed which leaves the active site of the enzyme thereby making it free for another reaction to take place.
In conclusion, the ACTIVE SITE of an enzyme is the region of an enzyme that attaches to a substrate allowing chemical reaction to take place.