JEE Advanced levelSingle correct optionDifficulty 3 of 3bm220
The dinucleotide 5-prime ApU 3-prime (ribose in both) has a free 5-prime OH and a free 3-prime OH, with one phosphodiester linkage from the 3-prime oxygen of the adenosine part to the 5-prime oxygen of the uridine part. It is completely hydrolysed to adenine, uracil, two ribose molecules and phosphoric acid. Counting one water for each P-O ester bond and each N-glycosidic bond cleaved, the number of water molecules consumed is
A2
B4
C3
D5
Answer: B
The single phosphodiester has two P-O ester bonds (to the 3-prime O and the 5-prime O): 2 water molecules. The two N-glycosidic bonds (base to C-1 of each ribose): 2 water molecules. Total 4.