The number of oxygen present in a nucleotide formed from a base, that is present only in RNA is ______

We need to find the number of oxygen atoms in a nucleotide formed from a base present only in RNA.

Identify the base present only in RNA.

Uracil (U) is the base that is present only in RNA (DNA has thymine instead).

Identify the components of the nucleotide.

A nucleotide = Nitrogenous base + Sugar (ribose) + Phosphate group

The nucleotide formed from uracil is Uridine 5'-monophosphate (UMP).

Count the oxygen atoms in each component.

Uracil ($$C_4H_4N_2O_2$$): 2 oxygen atoms (two carbonyl oxygens)

Ribose sugar in the nucleotide: The ring oxygen (1) + 2'-OH (1) + 3'-OH (1) = 3 oxygen atoms

(The 1'-O is the ring oxygen, the 5'-OH is used for the phosphoester bond, and the 1'-position connects to the base via an N-glycosidic bond, not involving oxygen)

Phosphate group ($$PO_4$$): The phosphorus is bonded to 4 oxygens. One oxygen connects to the sugar (5'-position). The remaining = 4 oxygen atoms (including the bridging O to sugar)

Total oxygen count.

Total = 2 (uracil) + 3 (ribose: ring O, 2'-OH, 3'-OH) + 4 (phosphate group) = $$\textbf{9}$$ oxygen atoms