Question

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

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct and Reason is NOT the correct explanation for Assertion
• C. Both Assertion and Reason are incorrect
• D. Assertion is correct but Reason is incorrect
• E. Assertion is incorrect but Reason is correct
• F. Answer reqiured

Answer 1

Answer: (B)

Both Assertion and Reason are correct and Reason is NOT the correct explanation for Assertion

Option (B) is correct.
$A$ : Enzymes have active sites that hold substrate molecule for a chemical reaction. The substrate is held at the active site in a suitable and right position, for effective attack of reagent. This can be explained by lock and key model. The forces between the active site and substrate can be covalent bond, hydrogen bond, van der waal's forces etc.
$R$ : Drugs compete with natural substrate by attaching covalently to the active site of enzyme. Many drugs acts as enzyme inhibitors. Inhibition by particular chemicals can be a source of insight into the mechanism of enzyme action: specific inhibitors can often be used to identify residues critical for catalysis.