Question

Match the class of compounds given in Column I with their functions given in Column II.

Column I	Column II
(i) Antagonists	(a) Communicate message between two neurons and that between neurons to muscles
(ii) Agonists	(b) Bind to the receptor site and inhibit its natural function
(iii) Chemical messenger	(c) Crucial to body’s communication process
(iv) Inhibitors	(d) Mimic the natural messenger
(v) Receptors	(e) Inhibit activities of enzymes

Answer 1

Column I	Column II
(i) Antagonists	(b) Bind to the receptor site and inhibit its natural function
(ii) Agonists	(d) Mimic the natural messenger
(iii) Chemical messenger	(a) Communicate message between two neurons and that between neurons to muscles
(iv) Inhibitors	(e) Inhibit activities of enzymes
(v) Receptors	(c) Crucial to body’s communication process

Explanation:

(i) Antagonist drugs are used when blocking of message is required. For example, dopamine antagonist is a drug which blocks the dopamine receptors by receptor antagonism.

(ii) Agonist drugs are useful when there is lack of chemical messenger, e.g., heroin.

(iii) These chemical messengers are received at the binding sites of receptor. These communicate message between two neurons and that between neurons to muscles.

(iv) Inhibitors block the binding site of the enzyme and prevent the binding of the substrate, or inhibit the catalytic activity of the enzyme.

(v) Receptors are proteins that are crucial to body’s communication. They are embedded in the cell membrane in such a way that their small part possessing active site projects out of the surface of the membrane and opens on the outside region of the cell membrane.