JEE Main · 2022 · 26 Jun 2022 · Shift 1 · Biomolecules

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

Answer: 9

Solution

The base present only in RNA is uracil. A nucleotide consists of a nitrogenous base, a ribose sugar, and a phosphate group. Uracil has 2 oxygen atoms. Ribose (

C_{5} H_{10} O_{5}

) contributes 5 oxygen atoms. The phosphate group (

PO_{4}^{3 -}

) contributes 4 oxygen atoms. However, when forming the nucleotide, one oxygen is lost in the glycosidic bond formation and one in the phosphoester bond. Total oxygen atoms =

2 + 5 + 4 - 2 = 9

oxygen atoms.

Structure Uracil structure — Uracil structure

Structure Nucleotide structure — Nucleotide structure

JEE Main · 2022 · 26 Jun 2022 · Shift 1 · Integer answer

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