To determine the number of oxygen atoms in a nucleotide formed from a base present only in RNA, we need to consider the components of such a nucleotide. RNA contains the base uracil, which replaces thymine found in DNA. An RNA nucleotide consists of three parts: a nitrogenous base (uracil), a five-carbon sugar (ribose), and a phosphate group.
1. **Uracil Structure**: Uracil, the base unique to RNA, is a pyrimidine with the molecular formula C4H4N2O2, containing 2 oxygen atoms.
2. **Ribose Sugar**: The sugar in RNA is ribose (C5H10O5), contributing 5 oxygen atoms.
3. **Phosphate Group**: A nucleotide contains one phosphate group (PO4), which adds 4 more oxygen atoms.
Thus, the total number of oxygen atoms in an RNA nucleotide is calculated as follows:
Oxygens in uracil = 2
Oxygens in ribose = 5
Oxygens in phosphate = 4
Total oxygens = 2 + 5 + 4 = 11
However, the typical structure combines the phosphate with the ribose and base reducing repetitive content, resulting in 9 distinct oxygens due to structural overlaps in the molecular connectivity. Thus, the number of oxygens in an RNA nucleotide is 9, fitting the specified range. Therefore, the number of oxygen atoms is 9.
