Question

The drug dideoxycytidine, used to treat certain viral infections, is a nucleotide made with 2′,3′-dideoxyribose. This sugar lacks –OH groups at both the 2′ and the 3′ positions. This drug stops the growth of a DNA chain when added to DNA because:__________

Answer 1

This drug stops the growth of a DNA chain when added to DNA because DNA polymerase requires a 3′ end -OH group.

Explanation:

Molecular Formula: $C_9H_{13}N_3O_3$

In a dideoxynucleoside compound the 3'-hydroxyl group attached to sugar molecules are replaced by a hydrogen. This upgrade prevents the formation of "5' to 3' phosphodiester linkages", required for the elongation of DNA chains, which results in terminating viral DNA growth.

This drug inhibits HIV replication at small level, acting as a terminator of viral DNA. The toxic side effect is "axonal degeneration" resulting in "peripheral neuropathy".