Note: In the following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.

Assertion : Enzymes have active sites that hold substrate molecule for a chemical reaction.


Reason : Drugs compete with natural substrate by attaching covalently to the active site of enzyme.



Enzymes do have active sites that hold substrate molecules for certain chemical reaction in a living organism.


This active site of enzymes usually holds the substrate molecule at a suitable orientation so that the substrate can interact with the reagent molecules.


Substrates bind to the active sites through ionic bond, H-bonding, van der Waals interaction or dipole-dipole interaction.


Whereas, drugs inhibit the activities of enzymes by blocking the active sites & prevent the binding of the substrate to the site and thus disrupts the catalytic activity of enzymes.


Therefore, drug’s competition with the suitable natural substrates by attaching covalently to active site of enzyme cannot be the reason for the given assertion statement.

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