Question

The correct match between Item I and Item II is :

Item I		Item II
(A)	Allosteric effect	(P)	Molecule binding to the active site of enzyme
(B)	Competitive inhibitor	(Q)	Molecule crucial for communication in the body
(C)	Receptor	(R)	Molecule binding to a site other than the active site of enzyme
(D)	Poison	(S)	Molecule binding to the enzyme covalently

• A. (A)\(\rightarrow\)(P); (B)\(\rightarrow\)(R); (C)\(\rightarrow\)(Q); (D)\(\rightarrow\)(S)
• B. (A)\(\rightarrow\)(P); (B)\(\rightarrow\)(R); (C)\(\rightarrow\)(S); (D)\(\rightarrow\)(Q)
• C. (A)\(\rightarrow\)(R); (B)\(\rightarrow\)(P); (C)\(\rightarrow\)(S); (D)\(\rightarrow\)(Q)
• D. (A)\(\rightarrow\)(R); (B)\(\rightarrow\)(P); (C)\(\rightarrow\)(Q); (D)\(\rightarrow\)(S)

Hint:

An allosteric effect arises from binding away from the active site; competitive inhibitors compete at the active site; receptors are communication proteins; poisons bind irreversibly (covalently).

Answer 1

The Correct Option is D

(A) Allosteric effect: an effector (allosteric inhibitor) binds to an allosteric site, which is a site other than the active site, changing the shape of the active site. Match: (R).
(B) Competitive inhibitor: resembles the substrate and binds to the active site, blocking it. Match: (P).
(C) Receptor: proteins (e.g. on cell surfaces) that receive chemical messengers, so they are crucial for communication in the body. Match: (Q).
(D) Poison: binds covalently (irreversibly) to the enzyme and permanently inhibits it. Match: (S).
Answer: (4) (A)\(\rightarrow\)(R); (B)\(\rightarrow\)(P); (C)\(\rightarrow\)(Q); (D)\(\rightarrow\)(S)